Saute the onions and garlic in butter until softened. Mix the ground turkey, mango chutney, sriracha, cilantro and salt and pepper. Shape into 8 sliders size patties.
Sear the turkey burgers in batches 3 minutes each side. Do not cook all the way through. remove and set aside.
Preheat oven 400 degrees. Line a baking sheet with parchment paper and oil the paper.
Roll out the puff pastry on floured board. Cut each sheet into 4 squares. Place a piece of cheese in the middle of each square. Brush whole grain mustard on each piece of cheese. Top with turkey burger.
Brush all sides with beaten egg. Fold dough over each patty sealing the edges and cut off excess dough. Brush the entire sliders with egg. Score the top for venting.
Place on baking sheet and bake for 15 minutes until golden