Preheat oven to 350 F and line a baking sheet with parchment paper.

In a medium bowl, combine the indgredients for the crumble. Stir them together with a spoon or mix them with a hand held mixer until combined and mixture forms small clusters. Spread the mixture evenly on the baking sheet. Bake for 10 minutes.

Remove from oven and allow to cool completely. Break up larger clumps with your hands or a fork if too large. (I prefer to have a mix of some small and some just slightly larger chunks). 

In a large bowl or bowl of an electric mixer, whip the heavy cream on high speed just until stiff peaks form.

Carefully fold in the sweetened condensed milk, vanilla and salt until well combined. Fold in the birthday cake crumbles and sprinkles. Pour mixture into a or a 9 x 5 x 3 inch bread tin, or 9 x 9 inch square pan lined with parchment paper, cover with plastic wrap and aluminum foil and freeze in the coldest part of your freezer for 4-6 hours.