These make-ahead freezer turnovers have been a family favourite at our house for well over 30 years. They are a bit finicky to make, so get everything done and form them one evening when watching a great movie.
Mix cream cheese and 1/2 cup butter
Add flour until fully incorporated and form into a ball; divide and set one ball aside, covered lightly at room temperature while making filling and wrap the other in plastic and chill
Place flour and butter into mixing bowl and pulse for 2 seconds on Turbo 2-3 times until mealy
Place cream cheese into mixing bowl and pulse for 2 seconds on Turbo 2-3 times until ingredients begin to form into a ball
Remove ingredients from mixing bowl to another bowl or place on the counter and form into 2 balls by hand; wrap one in plastic and chill and set the other aside, covered lightly at room temperature while making filling
Melt 2 tablespoons of butter in a large skillet; add mushrooms, onion, thyme, salt and pepper
Heat just until thickened; remove from heat
Mixture should not be runny: it should sit in a mound on the pastry without spreading
On a lightly floured surface, roll dough to less than 1/4 inch thickness; cut into 2.5 inch rounds with fluted cutter
Place small amount of filling in the middle of each circle (a heaping teaspoon); dot water along inside edge of each pastry circle to seal
Fold dough over filling to form a half-circle; press to seal dampened edges
Place on cookie sheet lined with parchment paper; press edges with a fork and puncture each decoratively to release steam while cooking OR recut sealed edges with the cutter, as illustrated
Pre-heat oven to 375°F if baking immediately
Brush with egg yolk and freeze on parchment-lined cookie sheet overnight; then package into labelled and dated zip-lock freezer bags
Remove from freezer, place on parchment-lined cookie sheet and bake frozen at 400°F for 15 – 18 minutes, until golden