Line a 4- to 6-quart slow cooker pot with parchment paper. Grease the parchment paper with the butter.

In a bowl, whisk the eggs, almond milk, sea salt, and black pepper. Add the spinach and mix to combine.

Pour the egg mixture into the prepared slow cooker pot.

Cover and cook on LOW for 4 hours or until the eggs are set.

Serve sprinkled with the feta cheese and sesame seeds.