Make pastry dough by placing flour, butter, egg yolk, powdered sugar, and salt in food processor and pulsing until texture resembles a course meal. Add water tablespoon by tablespoon. Assemble dough into small ball, wrap in plastic film and flatten to 1-inch circle. Chill for 30 minutes.
Roll out dough and cut into 4 1/4-inch rounds and let chill for another 30 minutes.
Preheat oven to 400 degrees.
Make caramel in non-reactive pan with sugar and water. Heat 6 (5-inch) cast iron blini pans, or 6 (8-ounce) ramekins in the oven.
When sugar and water is a warm amber color, place pan in bowl of cold water to stop cooking. Pour caramel into hot pans, and fill with mango slices. Brush mango slices with melted butter. Prick pastry rounds with fork and place on top of mangoes. Bake in a 400-degree oven for 25 minutes or until pastry is browned.