Prepare Pan: Do not preheat the oven. Liberally butter and flour a 10-inch tube pan. Set aside.
Cream Mixture: In the bowl of a stand mixer, cream together the butter, shortening, vanilla, brown sugar, and granulated sugar. Beat for 2 minutes or until creamy and light beige in color.
Add Eggs: Add the eggs one at a time, beating well after each addition, and scraping the sides of the bowl as needed.
Combine Dry Ingredients: Sift together the flour, baking powder, and salt. Lower the mixer speed and add the dry mixture to the creamed mixture alternately with the buttermilk. After all is added, increase the mixer speed to medium and beat until fully combined (around 45-60 seconds).
Add Pecans and Toffee Bits: By hand, mix in 1 1/2 cups pecans and toffee bits. Spread the batter into the prepared pan.
Bake: Place the cake into a cold oven. Bake at 325°F for 1 hour 30 minutes to 1 hour 45 minutes or until a long skewer inserted into the center comes back clean.
Cool: Cool in the pan on a cooling rack for 30 minutes, then turn onto the rack to cool completely.
Make Glaze: In a deep microwave-safe bowl, melt the butter in the microwave. Whisk in the brown sugar and heavy cream, then return to the microwave. Cook on high for 2 minutes. Remove from the microwave and stir in the vanilla and 1/4 cup pecans. Allow to cool slightly, then drizzle over the cake.
Notes:
I recommend baking this cake in a 10-inch tube pan. If using a standard-size bundt pan, place it onto a sheet pan to catch drips.
