Preheat your oven to 375 degrees.

Shred the potatoes and squeeze them dry using a clean kitchen towel. Place the shredded potatoes in a bowl and season them with salt, pepper, and olive oil.

Crack 12 eggs into a bowl. Add 1/4 cup of milk, 1/4 cup of flour, and salt and pepper to taste. Whisk until the mixture is thoroughly combined. It's ok if there are a few small lumps of flour.

Heat up 2 teaspoons of olive oil in a pan on medium heat. Toss in your veggies (except the spinach) and season with salt and pepper. Cook for 3-4 minutes, until the veggies are tender, but not browned.

Once they're cooled, toss your veggies into the beaten egg mixture, and toss into the spinach and cheese. Mix it up.

Line the bottom of your mini muffin cups with about 1 tbsp of shredded potatoes. Spoon some of the veggie/egg mixture into each cup, over the potatoes.

Bake at 375 degrees F until the egg mixture puffs and is just set in the center, about 8 to 10 minutes. Check doneness by pushing a clean toothpick into the center of the frittata. If it comes out clean and not wet, it's done.

Pop them out of the muffin tin using a fork or tongs. Serve warm.