Preheat oven to 400 F. Cut acorn squash in half (either way will work). Rub with 1 tablespoon olive oil, salt and pepper. Roast in preheated oven for 35-40 minutes, until soft and lightly golden.

While squash in the oven, in a large pan, add remaining olive oil. Add diced onion and sauté, stirring occasionally for 5-8 minutes, until soft.

Add ground beef, using a spoon to break up into small pieces. Cook beef, stirring occasionally, for about 8 minutes, until an internal temperature of 145 F is reached.

Pour in tomato sauce and stir to combine. Let simmer for about 10 minutes, until sauce has thickened. Add salt and pepper to taste.

Serve meat sauce in roasted acorn squash halves. Store leftovers in an airtight container in the fridge for 3-4 days.