Grease the bundt pan by spraying evenly with nonstick baking spray or you can spread softened butter all around the inside of the pan, and shake 1-2 Tbsp. flour around to coat. (Pro tip: Save your butter wrappers and use them to grease the loaf pan).
Open the cinnamon roll packages (reserve the frosting for later) and separate the rolls. Cut each cinnamon roll in fourths, place in a large bowl and set aside.
In a small bowl, combine the brown sugar and cinnamon together. Set aside.
3/4 cup brown sugar, packed, 2 tsp. ground cinnamon
Place diced apples in medium sized bowl. Mix 1/4 cup of the brown sugar mixture into the apples and stir.
2 large Granny Smith Apples, peeled and diced small
Mix the remaining brown sugar mixture with the cinnamon roll pieces. Coat them evenly.
Place half of the apples down in the bundt pan first, followed by half of the cinnamon roll pieces. Add the remaining apples and followed by the rest of the cinnamon rolls in an even layer.
Mix melted butter and rum together, pour on top of monkey bread.
1/3 cup unsalted butter, melted, 3 Tbsp. Rum
Bake for 45 minutes. Once done, remove from oven and let cool for 10 minutes. Carefully flip bread onto a plate and drizzle with reserved frosting. Enjoy warm!