Bake for 40-45 minutes
Combine cake mix, instant pudding, milk, eggs, sour cream, and vanilla extract until you have a thick batter, then pour it into the pan.
After baking, poke holes in the warm Bundt cake and pour the glaze into the holes and over the cake, allowing it to cool completely in the pan.
To prepare the butter glaze, melt butter, granulated sugar, water, and vanilla extract in a saucepan without boiling.
Store any leftover cake by covering it with plastic wrap and refrigerating it, or freeze it for up to 3 months.
To serve, turn the cake onto a plate, dust with powdered sugar, and optionally garnish with whipped cream and fresh berries.