Preheat oven to 375°F (190°C). Line a baking sheet with parchment paper.
Clean mushrooms with a damp paper towel and remove stems.
In a small bowl, mix together olive oil, garlic powder, onion powder, smoked paprika, salt and pepper.
Brush the mushrooms on both sides with the oil mixture.
Place the mushrooms on the prepared baking sheet and bake for 20 minutes.
Remove from oven and let cool before assembling burgers.
To assemble burgers: Place mushroom caps onto buns or rolls. Top with desired toppings such as lettuce, tomato, vegan mayo, mustard, ketchup etc. Serve immediately.