Preheat oven to 325°F (165°C). Grease and flour a bundt or loaf pan.

Make cake batter: Cream butter, shortening, sugar, and Jell-O until fluffy. Add eggs one at a time. Mix in vanilla.

In a separate bowl, whisk flour, baking soda, and salt. Add to batter alternately with sour cream and hot water.

Pour into pan and bake for 65–75 minutes, or until a toothpick comes out clean. Cool completely.

Frosting: Beat cream cheese and butter until smooth. Mix in powdered sugar, milk, and vanilla until creamy.

Crunch topping: Pulse Oreos in a food processor into crumbs. Stir in reserved Jell-O and melted butter.

Assemble: Spread frosting over cooled cake. Sprinkle generously with crunch topping.