1sheet frozen puff pastrythawed per manufacturer's instructions
salt and black pepper
1/3cupmixture of grated parmesanmozzarella and pecorino romano cheeses, plus extra for garnish
1poundvery thinly sliced Yukon gold baby potatoesI used the smallest setting on my mandolin
2tablespoonsfresh parsleychopped, plus extra for garnish
egg wash1 egg beaten with a tablespoon of water
Garnishes: crushed red pepperfresh parsley, grated cheese
Preheat your oven to 425 degrees F. Cut the puff pastry into 4 squares. About 1/4 inch in from the edges, score a square with a sharp knife. Poke the interior with a fork. Set the squares aside.
In a nonstick skillet, set over medium heat, add the butter. Melt the butter and cook until brown bits begin to form on the bottom of the pan. Once the brown bits begin to form, decrease the heat to medium low and whisk in the flour. Whisk for 1 minute and then whisk in the heavy cream. Let it thicken for just a minute (this won't take long) and then season with salt and black pepper. Whisk in the cheese until melted and then add the potatoes, rosemary and parsley. Toss to coat and then remove the pan from the heat.
Very carefully, add a decent amount of the potatoes to the center of the puff pastry squares. You may need to pile them just a tad. This is OK, once they begin to bake, the edges will puff up around the potatoes. Brush the edges with the egg wash and then transfer the squares to a large baking sheet that has been lined with parchment paper or a silicone baking mat. Transfer the baking pan to the oven and bake for 15-20 minutes or until the edges are brown and the potatoes are tender.
Remove the tarts from the heat and sprinkle with additional parsley, crushed red pepper and grated cheese. Enjoy immediately!
These tarts can very quickly get dry if there is not enough potato mixture. I like to serve them with hollandaise for some added flavor!