Wash the peaches thoroughly and pat them dry. Remove the pits and slice the peaches thinly. Place them in a bowl with lemon juice and gently toss them to prevent browning.

Lightly flour your work surface and unfold the thawed puff pastry. Roll it gently if needed. Cut twelve pastry circles that fit comfortably inside the muffin cups.

Lightly grease the muffin tin with butter or cooking spray. Place one pastry circle into each cup. Press the pastry gently against the bottom and sides without tearing it.

Add softened cream cheese and sugar to a mixing bowl. Beat until smooth and creamy. Add the egg yolk and vanilla, then mix again until everything is evenly combined.

Spoon a small amount of cream cheese filling into each pastry cup. Do not overfill them because the filling expands slightly during baking. Leave enough space for the peach slices.

Arrange two or three peach slices over each cream cheese filling. Press them gently into the filling. Keep the slices slightly overlapping for a pretty and colorful tart topping.

Mix the flour and cinnamon together in a small bowl. Sprinkle a very small amount over the peach slices. This adds gentle warmth and helps balance the fresh fruit flavor.

Preheat the oven to 375°F. Place the muffin tin in the oven and bake for 18 to 22 minutes. The pastry should become golden and crisp around the edges.

While the tarts bake, combine apricot jam with one tablespoon of water. Warm the mixture gently until smooth. Stir well so the glaze becomes easy to brush over the peaches.

Remove the baked tarts from the oven and let them cool for several minutes. Brush the warm apricot glaze lightly over the peaches. Transfer the tarts to a cooling rack.

Let the mini tarts cool completely or serve them slightly chilled. Dust the tops with powdered sugar just before serving. Arrange them on a simple platter for an elegant presentation.