Preheat oven to 450 degrees.

Prepare a rimmed baking pan with parchment paper or use pizza stone.

Steam the cauliflower until it is soft, adding the spinach for the last minute or two.

Drain well.  (I like to squeeze the excess moisture out by wringing the vegetables out in a clean tea towel.)  Transfer to a food processor and process until smooth.

Add the egg whites, 1 cup of mozzarella cheese, herbs and salt. Process until combined, scraping down sides as needed.

Spread the mixture in an even layer in small rounds on the prepared baking sheet or pizza stone.

Bake for about 15-17 minutes or until the crust begins to turn a darker golden brown around the edges.

Remove from the oven, then add sauce and cheese.

Return to oven for 2-3 minutes or until cheese is melted and gooey.