Special equipment: a 2-inch round cookie cutter
Place a rack in the center of the oven and preheat to 475 degrees F. Toss the mushrooms with 1 teaspoon of olive and the salt and roast on a baking sheet until they are golden brown, 6 to 8 minutes. Set the mushrooms aside.
Roll out the pizza dough to 1/4-inch thickness. Use a 2-inch round cookie cutter to cut out circles in the dough and transfer the circles to a parchment-lined baking sheet. Drizzle the dough circles lightly with olive oil. Place a teaspoon of mozzarella on each circle, then top with the mushrooms and kale, then the gorgonzola. Drizzle a little more olive oil over each pizzette and bake until they are golden and bubbly, about 10 minutes. Arrange the pizzette on a platter and serve immediately.