Preheat the oven to 300 degrees F. If you have a convection oven, set on convect. Line a large baking sheet with parchment paper.
Separate the egg whites and egg yolks. Place the whites in a stand mixer with a whip attachment. Add the cream of tartar and beat on high until the froth turns into firm meringue peaks. Move the meringue to a separate bowl.
Place the cream cheese in the empty stand mixing bowl. Beat on high to soften. Then add the egg yolks one at a time to incorporate. Scrape the bowl and beat until the mixture is completely smooth. Then beat in the Italian seasoning, salt, and garlic powder.
Gently fold the firm meringue into the yolk mixture. Try to deflate the meringue as little as possible, so the mixture is still firm and foamy. Spoon the mixture onto the baking sheet and spread into an even 12-inch circle.
Bake on convect for 15 minutes, or in a conventional oven for 20 minutes. The crust should be golden on the outside and firm. The center should not jiggle when shaken.
Set the oven temperature to 400 degrees F. Spread the crushed tomatoes over the top of the crust, leaving a 1/2 inch rim around the edges. Arrange the mozzarella slices over the tomato sauce. Then sprinkle with chopped kale. Finally tear the sliced prosciutto into smaller pieces and arrange them on the pizza.
Bake on the lower rack for 10 minutes, until the cheese is melted and the crust is a dark golden-brown. Sprinkle the top with fresh basil leaves before cutting and serving.
Make sure no egg yolk breaks into the whites. If any fat is incorporated, the meringue will not whip.