Preheat oven to 350 degrees and position oven rack one level below the center. Lightly butter an 9 by 12 inch baking dish, or similar sized casserole dish, set aside.
Place sliced plums and apples in a large bowl then pour Blue Chair Bay Vanilla Rum over the fruit and gently toss with hands to evenly coat.
In a medium mixing bowl whisk together granulated sugar, brown sugar, flour, cinnamon, nutmeg, star anise, and orange zest.
Add the sugar and spice mixture to the bowl of fruit and toss again until evenly coated.
Spoon filling into prepared pan. Next prepare your crisp topping.
In a large mixing bowl, whisk together flour, granulated sugar, brown sugar, oats, and cinnamon.
Pour melted butter into the mixture and stir with a fork until large crumbles form. Don't over mix and leave some of the topping chunky.
Sprinkle the oat mixture evenly over top of the fruit.
Bake in preheated oven for 45-50 minutes until top is golden brown and fruit filling is bubbling around the side.
Place pan on cooling rack for about 15-20 minutes before serving.