This is a creamy, dairy-free pasta sauce built from roasted red bell peppers, roasted garlic, sautéed onion, nutritional yeast, and unsweetened oat milk — blended smooth and tossed with spaghetti. It comes together in about the time it takes to boil pasta, and the sauce genuinely tastes richer than its ingredient list suggests. If you’ve been nervous about cooking plant-based, this is a solid place to start.
Smart swaps
- Nutritional yeast: This is a flaky, deactivated yeast sold near the health food or bulk section — not baking yeast. It adds a savory, slightly cheesy depth. If your store doesn’t carry it, a teaspoon of white miso stirred in at the end gets you close.
- Oat milk: Use unsweetened, plain oat milk — not the barista or flavored versions. Almond milk works too and gives a slightly thinner result. For a noticeably richer sauce, blend in two tablespoons of raw cashews with the other sauce ingredients.
- Spaghetti: Any long pasta works — linguine, fettuccine, or bucatini. For gluten-free, a brown rice spaghetti holds up well here since the sauce is thick enough to coat it properly.
Before you start
The one technique that makes or breaks this recipe is how long you roast the peppers. You want the skins genuinely blackened and blistered — not just softened. That char is what loosens the skin so it peels off cleanly, and it’s also what converts the pepper’s raw sharpness into sweetness. Pull them out too early and the sauce will taste flat. Once they come out of the oven, sealing them in a covered bowl for ten minutes lets steam do the peeling work for you, so don’t skip that rest. Everything else in this recipe is forgiving.
What can go wrong
- Sauce turns out watery: This usually means the roasted peppers weren’t drained well enough — they hold a lot of liquid. Pat them dry with a paper towel after peeling before adding them to the blender.
- Sauce tastes bitter: Pepper skin left in the sauce is the culprit. Take your time peeling — even small bits of charred skin can make the whole batch taste off.
- Sauce breaks or looks grainy after reheating: Oat milk can separate if you reheat it over high heat. Warm the sauce slowly over low heat and stir constantly, adding a splash of pasta water to bring it back together.
- Pasta clumps before serving: If you’re not saucing the pasta immediately, toss the drained spaghetti with a small drizzle of olive oil right away. It prevents the noodles from sticking into a solid mass while you finish the sauce.
- Sauce tastes one-dimensional: Taste before serving and adjust. A pinch more salt, a small squeeze of lemon juice, or an extra tablespoon of nutritional yeast can each pull the flavor into focus depending on what’s missing.
Make-ahead notes
The roasted red pepper sauce keeps well in a sealed container in the fridge for up to four days — it actually tastes better on day two once the flavors settle. You can also freeze the sauce in portions for up to two months; thaw overnight in the fridge before reheating. Cook the pasta fresh when you’re ready to eat rather than storing it sauced, since spaghetti absorbs the sauce and turns mushy. Reheat the sauce gently on the stovetop over low heat with a splash of water or plain oat milk to loosen it back to the right consistency — skip the microwave for this one, it heats unevenly and can make the sauce grainy.
Spaghetti with Roasted Red Pepper Sauce
Equipment
- rimmed baking sheet
- Blender or food processor
- Large pot
- Sauté pan
Ingredients
For the Roasted Red Pepper Sauce:
- 3 medium red bell peppers organic, halved and seeds removed
- 4 cloves garlic left in skins to roast
- 1 tbsp olive oil extra virgin
- 1 cup yellow onion finely chopped
- ½ tsp crushed red pepper flakes optional, for gentle heat
- 2 tbsp nutritional yeast for umami depth
- 1 tsp sea salt
- ¼ tsp freshly ground black pepper
- ½ cup unsweetened oat milk or substitute with almond milk for a nuttier flavor
For the Pasta:
- 12 oz spaghetti gluten-free if desired
- 1 tbsp olive oil
- 2 tbsp fresh basil chopped, for garnish
Instructions
- Preheat oven to 425°F (220°C). Line a rimmed baking sheet with parchment paper.
- Place red bell pepper halves and garlic cloves (in their skins) cut side down on the sheet. Roast for 25-30 minutes or until the peppers are charred and soft, and the garlic is caramelized.
- Meanwhile, heat 1 tablespoon olive oil in a sauté pan over medium heat. Add the chopped onion and cook for about 8 minutes, stirring occasionally, until translucent and slightly golden. Add red pepper flakes, if using.
- Cook the spaghetti according to package instructions until al dente. Drain, toss with olive oil, and set aside.
- Peel the garlic cloves. Add roasted peppers, peeled garlic, sautéed onions, nutritional yeast, salt, black pepper, and oat milk to a blender. Blend until smooth and creamy, about 1 minute.
- Pour the sauce into the sauté pan over low heat. Simmer gently for 5 minutes, stirring occasionally. Toss in the cooked spaghetti and mix until fully coated and heated through.
- Serve hot, garnished with fresh basil. Optional: drizzle lightly with extra virgin olive oil for shine and richness.
Notes
- Char the peppers more for deeper smoky tones.
- Use cashew cream in place of oat milk for a richer sauce.
- To caramelize onions faster, add a pinch of salt as they cook.
Nutrition
Your questions, answered
Can I use jarred roasted red peppers instead of roasting my own?
Yes, jarred peppers work and will save you about 30 minutes. Drain and rinse them well first, since the brine they’re packed in can make the sauce taste slightly pickled if you don’t.
I’ve never used nutritional yeast before — will the sauce taste weird without it?
The sauce will still be good without it, but it will taste noticeably less savory and complex. Nutritional yeast is worth buying — a bag lasts months and you can sprinkle it on anything from popcorn to roasted vegetables.
How do I know when the pasta is actually al dente?
Pull a strand out about two minutes before the package time says and bite through it — you’re looking for a very thin white line in the center, not fully soft all the way through. That line disappears quickly, so check early rather than late.
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