For the roasted tomatoes:
1½ pints grape or cherry tomatoes, halved
2 tbsp. olive oil
Coarse salt and freshly ground black pepper, to taste
Pinch of sugar
For the pasta:
12-16 oz. pasta (I use whole wheat)
2 tbsp. butter
1 tbsp. olive oil
¾ cup chopped yellow onion
3-4 cloves garlic, minced
½ tsp. red pepper flakes
16 oz. baby spinach leaves
1 avocado, split and pitted
6 tbsp. fresh basil leaves, packed
6 tbsp. greek yogurt
½ cup grated Parmesan cheese, plus more for serving
To roast the tomatoes, preheat the oven to 350˚ F. Combine the tomatoes, olive oil, salt and pepper, and sugar on a rimmed baking sheet and toss well to coat. Bake for about 40 minutes, tossing once or twice during cooking. Remove from the oven and let cool.
Bring a large pot of water to boil. Cook pasta according to the package directions. Drain, reserving ½ cup of the pasta water for use in the sauce.
While the pasta is cooking, melt the butter with the olive oil in a large sauté pan over medium-high heat. Add the onion to the pan and cook until softened, about 5 minutes. Stir in the garlic and red pepper flakes and cook about 1 minute more. Add the spinach to the pan, cover, and reduce the heat to medium. (If you can’t fit all the spinach at once it’s okay – just add it in batches as it wilts.) Stir occasionally until all the spinach has been wilted.
In the bowl of a food processor or blender combine the onion-spinach mixture with the avocado, basil, yogurt and Parmesan. Process until the mixture is smooth, adding in a splash of pasta water at a time as necessary to achieve a smooth consistency. Toss the sauce with the warm pasta noodles and serve immediately topped with the roasted tomatoes and additional Parmesan, if desired.