Preheat oven to 365° F. Spray a Bundt pan with nonstick cooking spray.
In a large bowl, mix together butter and sugar until light and fluffy. Add in eggs one at a time.
Beat in the buttermilk, lemon zest and vanilla.
Combine flour, baking powder and salt in bowl. Stir into creamed buttermilk mixture until moist then fold in blueberries.
Fill Bundt Pan with blueberry batter. Bake for 25-35 minutes or until an inserted toothpick comes out clean. Cool cake for about 5 minutes or so before removing from the bundt pan to a wire rackor plate to completely cool.
Meanwhile, in a small bowl, mix together powdered sugar, lemon juice, lemon zest, vanilla and heavy cream. Drizzle over cooled Bundt cake.