Preheat your broiler or preheat oven to 400℉. Cover a baking sheet with parchment paper.
In a mixing bowl, toss the butternut squash, olive oil, salt, and pepper until well combined.
Spread the butternut squash on the baking sheet in an even layer. Bake in the oven for 25-30 minutes or until golden brown and tender. Remove from oven and let cool.
For the Romesco Sauce: In a food processor or blender, place the roasted squash, tomatoes, red pepper flakes, garlic cloves, almonds, basil salt, pepper, red wine vinegar, and olive oil. Blend until smooth. If not coming out smooth, add a tablespoon of olive oil at a time until smooth.
Serve over your favorite pasta or your choice of protein.