Bring a pot of salted water to a boil and cook the whole wheat penne pasta according to the package instructions until al dente. Reserve about ½ cup of pasta water before draining, then set the pasta aside.
In the same pot, add the marinara sauce and heat over medium heat until it starts to bubble. Stir in the red pepper flakes for a touch of spice.
Add the sliced chicken sausage to the marinara sauce and cook for 2-3 minutes, stirring occasionally, until heated through.
Add the spinach to the pot and cook for 1-2 minutes, stirring, until the spinach is wilted. If the sauce is too thick, add a splash of the reserved pasta water to loosen it.
Add the cooked pasta to the pot and toss it with the sauce until evenly coated.
Divide the pasta into two servings and top with freshly grated Parmesan cheese, as desired.
Notes
Leftovers: Store in an airtight container in the refrigerator for up to 4 days.
Shopping Look for a marinara or pasta sauce with limited added sugar and olive oil.
