3sliceshearty or artisan bread, cut into 1/2-inch cubes, about 4 cups total (I used a homemade ciabatta loaf)
1mediumonion, finely chopped
2garlic cloves, finely minced
Salt and pepper
1poundradiatore pasta, or other small pasta shape
1pintcherry tomatoes, halved
1 (6-ounce)bagbaby spinach
1cupgrated parmesan cheese
Bring 4 quarts of water to a boil in a large pot. While the water comes to a boil, melt the butter in a large nonstick skillet over medium heat. Add the bread cubes and cook, stirring frequently, until golden brown, 6 to 8 minutes. Transfer to a bowl and wipe out the skillet.
Cook the chopped bacon in the empty skillet over medium-high heat until crisp, about 5 minutes. Transfer the bacon to a paper towel-lined plate and leave a small amount of the bacon fat in the skillet (about 2 teaspoons). Cook the onion in the bacon fat until softened, about 5 minutes. Add the garlic and 1/2 teaspoon pepper and cook until fragrant, about 30 seconds.
While the onion softens in the skillet, add 1 tablespoon salt to the boiling water then stir in the pasta. Cook until just tender (al dente). Reserve 1 1/2 cups of the pasta water by ladling it into a bowl before draining the pasta. Drain the pasta and return it to the pot. Stir in the tomatoes, spinach, Parmesan, bacon and onion mixture, and 1 cup reserved pasta water. Stir quickly and completely so the cheese doesn’t melt in large clumps. Add additional water as needed. Season with salt and pepper to taste. Ladle pasta onto plates or bowls and top with croutons. Serve immediately.