Step 1: Prep Oven and Pan
Preheat your oven to 325°F (163°C). To prevent the cake from sticking, ensure you thoroughly grease and flour a 10- or 12-cup Bundt pan.

Step 2: Combine Dry Ingredients
In a medium bowl, whisk together the flour, baking powder, and salt. This step is crucial for ensuring the leavening agents are evenly distributed, which leads to a consistent rise.

Step 3: Cream Fats and Sugars
In a large mixing bowl, beat the softened butter and shortening with an electric mixer until the mixture is smooth. Add the brown and granulated sugars and continue to beat on medium-high speed for 5-7 minutes. The mixture should become pale and fluffy, which incorporates air for a lighter cake texture.

Step 4: Add Eggs and Vanilla
With the mixer on a low speed, add the eggs one at a time, making sure each is well incorporated before adding the next. Once all the eggs are mixed in, add the vanilla extract and mix to combine.

Step 5: Alternate Wet and Dry
On a low speed, add the flour mixture in three parts, alternating with the buttermilk in two parts. Begin and end with the flour mixture. Be careful to mix only until the ingredients are just combined to avoid developing too much gluten, which can result in a tough cake.

Step 6: Fold-in and Bake
Gently fold the toasted pecans and toffee bits into the batter using a spatula. Pour the finished batter into your prepared Bundt pan and bake for 65-75 minutes. To check for doneness, insert a wooden skewer into the center of the cake; it should come out clean. Allow the cake to cool in the pan for 15 minutes before carefully inverting it onto a wire rack to cool completely.

Step 7: Make the Glaze
In a microwave-safe bowl, combine all the ingredients for the praline glaze. Microwave on high for 1 minute, then whisk until the glaze is smooth and well combined. Pour the warm glaze over the completely cooled cake.