Let dough rise according to package directions. Punch down; divide into 10 pieces. On a lightly floured surface, roll each piece into a 5-in. circle.
Preheat oven to 375°. Place 1 circle on a greased baking sheet; top with about 1/4 cup ham and 2 tablespoons cheese to within 1/2 in. of edge. Press filling to flatten. Combine egg yolk and water; brush edges of dough. Fold dough over filling and pinch edges to seal. Repeat with remaining dough and filling. Brush tops with remaining egg yolk mixture.
Bake until golden brown, 15-20 minutes. Serve warm or cold.
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