Roll out each pie crust disc between parchment, using a small amount of gluten free 1 to 1 flour or other gluten free flour. Invert each into the pie dishes. Cut the excess dough off just over the edge. Fold inside and pinch lightly with your thumb or forefinger, just below the top of the dish. (If using gluten-free, refrigerate for a half hour to an hour).
Preheat the oven to 400 degrees, with the rack in the center.
Divide the fruit in half. Decorate the tarts in a pattern if you like. Or just toss the apricots in and scatter the raspberries on top.
Combine the sugar and cornstarch. Sprinkle over the tarts, dividing evenly between the two.
Brush or sprinkle the lemon juice over the tarts, covering the cornstarch sugar mixture as much as possible. Next add butter pieces scattered on top. Bake tarts for 40-45 minutes, coverering the edge with foil strips or pie edging strips if browning too much.
Cool slightly or completely before serving. Serve with sweetened whipped cream or vanilla ice cream.