Preheat oven to 450 F.

Place spinach on a plate; microwave on high for 6 minutes to defrost.

Heat a medium skillet over medium-high heat with olive oil and butter.

Add onions, garlic, thyme, salt, and pepper; cook, stirring frequently, 4-5 minutes.

Squeeze out excess liquid from spinach.

Add spinach, heavy cream, chicken stock, and nutmeg to onion and garlic and stir to break up.

Bring mixture to a simmer; cook 2-3 minutes until creamy and thick.

Transfer to a small backing dish.

Create 4 divots in the spinach with a spoon.

Crack eggs, one at a time, into a small cup or ramekin and then slide egg into a divot.

Season eggs with salt and pepper.

Top with Gruyere cheese.

Bake 10-15 minutes according to egg preference.