Brown the fennel seed in a heavy skillet on medium heat. Stir seeds continually until they are browned, about 5 minutes. Cool and then grind in a spice grinder, (or a coffee grinder). If you don't have a grinder, you can leave them whole.
Mix all ingredients in a bowl and refrigerate.
Allow the flavors to meld by wrapping the pork in plastic wrap and refrigerating for 6 hours or overnight.
Brown the Italian sausage with 1 or 2 tbsp olive oil in a skillet.
Notes
Add more red pepper flakes if you like hotter sausage.
Calorie count is based on one serving of the pork only. (No spaghetti or marinara sauce).