Preheat the oven to 325°F (165°C). Grease and flour a 10-inch Bundt or tube pan, making sure to coat every corner so the cake won’t stick.
In a large bowl, beat the softened butter and sugar together for about 4–5 minutes until light and fluffy.
Add the eggs one at a time, mixing well after each one. Stir in the vanilla extract.
In another bowl, whisk together the flour, baking powder, and salt.
Add the dry mix to the butter mixture in parts, alternating with the buttermilk. Begin and end with the flour. Mix just until everything is combined—don’t overmix.
Gently stir in the crushed Oreos with a spatula. Don’t mix too much—you want big Oreo pieces in every bite.
Pour the batter into your prepared pan and smooth the top. Bake for 70–80 minutes, or until a toothpick comes out clean. The top should be golden and a little cracked.
Let the cake sit in the pan for 15 minutes, then carefully flip it onto a wire rack to cool completely.
Whisk powdered sugar, cream (or milk), and vanilla in a small bowl until smooth. Drizzle over the cooled cake, and sprinkle extra crushed Oreos on top if you like.