Do not preheat the oven. Liberally butter and flour a large bundt pan or tube pan or spray with baking spray. Set aside. (See Cook's note)
In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter, shortening, vanilla extract, brown sugar and granulated sugar. Beat for 2 minutes or until creamy and light beige in color.
Add the eggs one at a time beating well after each addition stopping to scrap the sides of the bowl as needed.
In a separate medium bowl use a whisk to sift together the flour, baking powder and salt.
On low speed add the flour mixture to the creamed mixture alternately with the buttermilk. After all has been added increase the speed of the mixer to medium and beat just until fully combined around 45-60 seconds.
By hand stir in 1 1/2 cup pecans and toffee bits into the cake batter. Spread into the prepared pan.
Place the cake into a cold oven. Bake at 325F for 1hr 30min to 1hr 45min or until a long skewer inserted into the center comes back clean.
Cool in the pan on a wire rack for 30 minutes then flip the cake onto the rack to cool completely.
Glaze: In a deep microwave safe bowl melt the butter in the microwave. Whisk the brown sugar and heavy cream into the melted butter then return to the microwave.
Cook glaze on high for 2 minutes. Remove from the microwave and stir in the vanilla and 1/4 cup chopped pecans. Allow to cool slightly then drizzle over the cake.
Store Pecan Praline Pound Cake in an airtight container chilled in the fridge for up to one week.
Toasting the Pecans: Spread chopped pecans on a baking sheet in a single layer. Place into a preheated 350°F oven toasting for 6-8 minutes or until lightly golden and fragrant. Allow to cool completely before adding to the batter.