Remove mushroom stems + using a spoon, scoop out the dark gills on the underside of the mushrooms, rinse + pat dry; heat 1 tbsp oil in a skillet over med-high + cook mushrooms 2-3 min per side until browned + tender; add salt/pep + set aside

Spread 1-2 tbsp pesto onto each bun, add mushrooms + top each with 2-4 tbsp cheese

Heat a lightly oiled skillet over med-high + toast sandwiches 3-4 min per side until golden + cheese melts—looks good!