Preheat your oven to 375°F (190°C).

In a large bowl, toss the diced peaches, blueberries, and blackberries with the lemon juice.

Mix the cornstarch, sugar, and cinnamon in a separate bowl.

Sprinkle the dry mixture over the fruit and gently toss to coat.

Remove the prepared crust from the refrigerator.

Spread the peach or apricot jam evenly over the crust.

Distribute the fruit mixture over the jam-coated crust.

Crumble the reserved dough from the Basic Crust and Topping Recipe over the fruit layer. For a rough surface, press some of the dough pieces together before crumbling them on top.

Bake in the preheated oven for 40-45 minutes or until the topping is golden brown and the fruit is bubbly. Cover the top loosely with foil if it begins to brown too quickly.

Remove the crisp from the oven and allow it to cool.

Garnish with the remaining fresh blackberries and serve warm with vanilla ice cream or whipped cream.