• Preheat the oven to 400 F.
• Add the crimini mushrooms to a large baking sheet. Toss with 2 tablespoons of olive oil, garlic powder, salt and pepper. Roast in the preheated oven for 10-12 minutes.
• While the mushrooms are roasting, brush the flatbread with the remaining 2 tablespoons of olive oil. Sprinkle each evenly with mozzarella and parmesan cheese.
• Add the roasted mushrooms on top of the flatbreads and place back in the oven for another 6-8 minutes, until the cheese has melted and starts to lightly brown.
• Drizzle each flatbread with balsamic glaze and top with arugula. Add extra parmesan cheese on top. Cut into slices and serve.

Balsamic glaze

• Add balsamic vinegar and brown sugar to a large saucepan over medium heat. Stir well until the sugar has dissolved.
• Let the mixture simmer for about 15 minutes, stirring occasionally, until it starts to bubble. The volume will have cooked down considerably.
• Let cool for a few minutes until the glaze is thick.