Preheat the oven to 400°F (200°C).
In a large bowl, whisk together eggs, almond milk, garlic, salt, and black pepper until fully combined. Set aside.
Choose your preferred vegetable variation and prepare as directed below.
For All Variations:
Heat olive oil in a 10- or 12-inch oven-safe skillet over medium heat.
Cook vegetables as instructed for the chosen variation until tender.
Pour the egg mixture into the skillet and gently shake to distribute evenly.
Add cheese as directed.
Transfer the skillet to the oven and bake for 15–20 minutes, or until the center is set and no longer jiggly.
Let cool slightly, slice, and serve.
This Frittata Recipe is done when the top is lightly golden and the eggs are perfectly set but still tender.