Adding Nom Nom Paleo's Magic Mushroom Powder to the mushrooms before roasting them really really dials up the level of umami in this easy to assemble tart.
1 pound cremini or button mushrooms, sliced to ¼ to ½-in. thickness
2 Tbs. olive oil
1 tsp. Nom Nom Paleo Magic Mushroom Powder (7232)
½ small yellow onion, thinly sliced
2 Tbs. creme fraiche or sour cream
1 sheet of puff pastry (from a 18.3-oz box that contains 2 sheets), thawed overnight in fridge
2 Tbs. heavy cream
6 ounces of gruyere, coarsely grated (about 2 cups)
2 Tbs. chopped parsley for garnish (optional)
Heat oven to 400F. Place mushrooms, olive oil, and Magic Mushroom Powder in a medium mixing bowl and toss to combine. Transfer mushrooms to a sheet pan and bake for 20-25 minutes, or until mushrooms are golden brown and most of the liquid released from them has cooked off.
Place the sliced onion in the same bowl that you used to toss the mushrooms. When the mushrooms come out of the oven, place them on top of the onion. Add the creme fraiche or sour cream and toss to combine. Let cool to room temperature.
Line a sheet pan with parchment paper. Unroll puff pastry onto parchment paper. Using a small sharp knife, score a ½-in. border around the edge of the dough, making sure not to cut all the way through. Use a fork to poke the area inside the border to help keep the middle from puffing up.
Using a small pastry brush, brush the heavy cream onto the border of the pastry. Sprinkle the gruyere cheese within the drawn border and evenly distribute the mushroom mixture over the cheese. Bake for 20-25 minutes, or until golden brown and the cheese is melted. Sprinkle with chopped parsley and serve warm or at room temperature.