Preheat oven to 400 degrees F. Line baking sheet with parchment paper.

In mixing bowl, use electric mixer to beat butter until softened.

Add sugar and beat until light and fluffy.

Add eggs, one at a time, until combined.

Add flour and salt until mixture forms into dough ball.

Flatten dough into disk and cover with plastic wrap; refrigerate 30 minutes.

Divide dough in half; roll to ¼”-thick round.

In bowl, mix together mascarpone, lemon juice and sugar.

Into center of crust circle, pour mixture evenly; top with blueberries

Fold crust edges around filling to form galette.

Using pastry brush, paint melted butter over crust; sprinkle with granulated sugar.

Arrange tart on baking sheet; bake 20 minutes or until lightly browned