Preheat oven to 400℉ (200℃). Line a baking sheet with parchment paper.
Whisk eggs and Greek yogurt until smooth. Mix dry ingredients separately, then combine with wet mixture. Fold in spinach, ½ cup cheddar, and optional add-ins.
Scoop dough onto the baking sheet using a greased ⅓ cup measure. Top with remaining cheddar and flatten slightly.
Bake for 20 minutes until golden brown. Serve warm.
Notes
For extra flavor, add fresh herbs or diced red bell pepper.