Preheat the oven to 350 degrees F.
Heat a large skillet over medium-high heat. Add the oil and mushrooms. Season with a pinch of salt and cook, stirring, until the mushrooms are tender and dark brown, about 5 minutes.
Spoon the pizza sauce over each piece of bread. For the kid versions, simply sprinkle each pizza with a small handful of pepperoni and cheese.
For the adults, top each pizza with the mushrooms, red onion, jalapeno and cheese. Arrange all of the pizzas on a rimmed baking sheet, and bake until the cheese is melted and starting to bubble, about 20 minutes.
Garnish with a little bit of fresh parsley and thyme, if using!