Preheat oven to 350 degrees F.

Butter the bottom and sides of a 9-by-13-inch baking pan.

Place a piece of parchment paper along the bottom of the pan, with some paper overhanging on the two short ends.

In a medium bowl, whisk together the flour, baking powder, salt and cinnamon.

In the bowl of a stand mixer, cream the butter and brown sugar at medium speed until light and fluffy, about 2 minutes; scraping the dough as needed.

Add the eggs, one at a time, beating until well combined; add the vanilla and beat into dough.

Add the dry ingredients and beat at low speed until just combined, about 30 seconds, scraping down the bowl as needed.

Fold in the chopped apples and toffee bits and spread the batter into the prepared pan.

Bake 25- 30 minutes, or until center is set and toothpick inserted into the center come out clean. Place on wire rack to cool completely before slicing or frosting.

To make the frosting, melt the butter in a small saucepan over low heat. Stir in the brown sugar, half and half and vanilla and bring the mixture to a boil; cook for one minutes then remove from heat and let cool to lukewarm.

Sift in the confectioners sugar until mixture is smooth; you can do this by hand but I was lazy and used my mixer.

Spread evenly over bars; sprinkle with chopped nuts and let them set at room temperature for about 30 minutes before cutting into squares.