Preheat the oven to 425 F.
Lightly spray a saute pan (large enough for the package of soyrizo) with cooking oil, I like Trader Joe's avocado oil. Turn the heat to medium.
Once the pan is hot, add the soyrizo and use a spatula to chop into ground meat and stir occasionally, until it's cooked though, about 5 minutes.
While it's cooking, crack the eggs into a bowl and stir together. Add in the milk, salt, and pepper and stir together to emulsify.
Once the oven is preheated and the soyrizo is cooked, spray the pie plate with the cooking spray. Use a brush to thoroughly cover the bottom and sides of the pan so the egg won't get stuck.
Evenly spread the soyrizo on the pie plate.
Pour the egg mixture evenly over the soyrizo.
Scatter the shredded cheeses evenly over the egg mixture.
Place in the oven for 15 minutes or until the eggs are set (don't jiggle anymore).
Optional: turn on the broiler for 2-4 minutes to brown the top to your liking.
Remove from the oven and let sit to rest for 5 minutes.
Cut into 4 even pieces and serve.
To reheat the next day, place a slice of frittata onto a piece of aluminum foil and put into the oven at 350 F for 5-7 minutes or until heated through.