Prepare the Rhubarb and Raspberries: Wash and trim rhubarb, chop into small pieces. Cook with sugar until softened, then fold in raspberries and allow to cool.

Cream Butter and Sugar: Beat butter and sugar until light and fluffy, about 3-5 minutes.

Incorporate Eggs: Add eggs one at a time to the mixture, beating well after each addition.

Mix Dry Ingredients: Whisk flour, baking powder, and baking soda. Gradually add to the butter mixture, alternating with sour cream.

Swirl the Fruit Mixture: Fold the cooled fruit mixture into the batter, creating swirls without overmixing.

Prepare for Baking: Preheat oven to 350°F (175°C), grease bundt pan, and pour in batter.

Bake the Cake: Bake for 45-55 minutes or until a toothpick comes out clean. Let it cool in the pan for 15 minutes.

Glaze the Cake: Whisk powdered sugar with milk and drizzle over the cooled cake.