Heat the oven to 325°F. Thoroughly grease and flour a 10-inch Bundt or tube pan, making sure the center tube is coated.

Whisk the flour, baking powder, and salt together in a medium bowl. Measure 1 to 2 tablespoons of this flour mixture and toss it with the pecans and toffee bits.

Beat the softened butter, shortening, and granulated sugar for 4 to 5 minutes, until pale and fluffy. Scrape the bowl so the mixture creams evenly.

Add the eggs one at a time, beating well after each addition. Scrape down the sides of the bowl as needed.

Add the flour mixture alternately with the milk, beginning and ending with the flour. Mix only until the ingredients are incorporated, then stir in the vanilla.

Fold the floured pecans and toffee bits into the batter by hand. Spoon the batter into the prepared pan and smooth the top.

Bake for 65 to 80 minutes, or until a skewer inserted near the center comes out with only a few moist crumbs. Cool in the pan for 10 to 15 minutes, then turn the cake onto a rack and cool completely.

For the glaze, melt the butter in a saucepan over medium heat. Add the brown sugar and cream or evaporated milk, bring the mixture to a gentle boil while stirring constantly, and cook for 2 to 3 minutes.

Remove the glaze from the heat and stir in the vanilla and optional salt. Let it cool briefly until slightly thickened, then pour or spoon it over the completely cooled cake and finish with extra pecans or toffee pieces if desired.