Taco Pasta

Name: Taco Pasta
Prep time: 10 min
Cook time: 15 min
Total time: 25 min
Cuisine: TexMex
Ingredients: 1 small yellow onion; 2 cloves garlic; 1 (2.25-ounce) can sliced black olives; 6 sprigs fresh cilantro; 4 ounces American cheese slices; 8 ounces sharp cheddar cheese; 1 pound dried medium pasta shells; 2 tablespoons unsalted butter; 1 pound lean ground beef; 2 tablespoons taco seasoning; 1 teaspoon kosher salt, plus more as needed; 1/4 cup all-purpose flour; 2 cups low-sodium beef broth; 1 (14.5-ounce) can diced tomatoes; 1/2 cup sour cream