Combine apples, cranberries, 1/4 cup flour, white sugar, lemon juice, and nutmeg in a large bowl; toss until apples are well coated. Spread over the bottom of a 9x13-inch baking dish.
Combine remaining 1 cup flour, brown sugar, oats, cinnamon, and vanilla extract in another bowl. Pour in melted butter; mix thoroughly. Spoon evenly over apple-cranberry mixture in the baking dish.
Bake in the preheated oven until apples are tender and top is browned, 50 to 60 minutes. Let cool slightly, 15 to 20 minutes.
Combine heavy cream, mascarpone cheese, and lavender honey in a bowl; beat with an electric mixer on medium speed until soft peaks form. Serve with warm crisp.
