In a food processor, combine the almond flour, parmesan, baking powder, psyllium husk, and salt. Pulse to mix. Then add in the diced cold butter and pulse again until the butter is cut into the dry ingredients. Finally, add in the egg and pulse one last time until the dough forms into a ball. Set it aside.

In a 9" cast iron skillet, carefully press out the Italian sausage into the base of the pan. Cook on medium heat on the stove until the bottom is browned. Carefully flip it and cook the otherside. When fully cooked, place on a paper towel to drain the grease. Allow the pan to cool while making the sauce.

In a small pot, add the crushed tomatoes, grated onion, garlic, salt, and Italian seasoning together. Allow it to cook down and break the tomatoes down more with a wooden spoon if necessary. Cook on low.

Grate the cheese and set it aside.

After par-baking, fill the deep dish pizza with the remaining layers. First, layer the dough with the cheese, add the sausage patty and then cover it with the sauce. Place it back on the grill on indirect heat (or oven) and continue to bake for another 15-20 minutes. The crust should be cooked, golden brown, and the sauce should be bubbly.

Remove from the heat and let sit for about 10 minutes before cutting and serving. Add some extra parmesan cheese over the top and sprinkle with red pepper flakes.