Spinach-Topped Bread

This is so incredibly simple. I can’t believe I didn’t think of this years ago.
1 large loaf of Italian bread
2 Tbsp. butter
1 small, diced onion
1 pkg. frozen spinach – thawed or not
1 tsp. minced garlic
Salt & pepper
1/2 cup Pecorino Romano or Parmesan
Preheat your oven to 350 degrees. Get out a cookie or baking sheet. Melt the butter in a small-medium saucepan and when hot, add the onion and the thawed or frozen spinach. Cook for about 10-15 minutes; if spinach was frozen it takes about this long to cook through. Sprinkle on the cheeses, salt, & pepper. Transfer to a food processor or blender (or not) and blitz till smooth.
Slice loaf of bread in half lengthwise and place each piece face up on the baking sheet. Spread the mixture on each half of bread (you may have leftovers) and place in the oven for about 15 minutes. Slice and serve.