Bring a large pot of salted water to boil for spaghetti. Cook according to package al dente. Reserve 1 1/2 cups of the pasta water before draining.
Meanwhile, In large deep saute pan or skillet (large enough to hold cooked pasta with sauce) add 1 tbs. olive oil and chicken sausage (season with a pinch of salt). Saute sausage over medium heat until browned, breaking up with a spoon as it cooks.
When sausage are browned, add garlic, crushed red pepper flakes and chicken bouillon cubes, cook for 2 minutes stirring a few times. Add tomatoes and cook for another 2 minutes then add 1/4 cup olive oil, butter, and reserved pasta water.
Bring to a boil and reduce to simmer, let cook for about 5 minutes. Add the spinach, cook for 1 minute just until it starts to wilt.
Remove from heat, and add the cooked spaghetti. Toss well to combine.