Preheat the oven to 375 degrees F and grease a mini muffin tin very well with nonstick spray.
Roughly cut up the spinach with kitchen scissors or a knife.
Add spinach to a medium bowl with the rest of the ingredients and stir well to combine.
Divide among the prepared mini muffin tin, using about 1 tablespoon batter in each cup.
Bake for 14-16 minutes or until the edges are golden brown and the tops are firm.
Place the muffin tin on a wire rack and let muffins cool in the tin for 5-10 minutes. As they cool, they will start to pull away from the sides of the pan slightly. Use a paring knife around the edges to gently loosen and remove the muffins from the pan.
Store in an airtight container for up to 5 days. Warm for 15 seconds in the microwave if desired.
Be sure to grease your muffin tin really well to avoid sticking.
To use frozen spinach, let it thaw and squeeze out any moisture. Use 1/4 cup and break it up.
Gluten-free: Use the cornmeal or a cup for cup gluten-free flour.
Dairy-free: Omit the cheese. You could add another cup of spinach or another veggie like corn or cooked roasted butternut squash.
You can omit the added salt if desired.
Run a paring knife around the edges of the muffins to help loosen if needed.
Cut into smaller pieces for older babies or one year olds as needed.