In a medium saucepan, combine butter, Truvia® Brown Sugar Blend, and salt.
Cook, stirring, over medium heat until butter is melted and Brown Sugar Blend is dissolved.
Cool 10-15 minutes.
Add egg and vanilla; then add flour and baking powder and stir until combined.
Stir in grated apple and 1/4 c. toffee chips.
Pour into greased 9x13 inch pan.
Bake at 350 degrees for 30 minutes.
Remove from oven; sprinkle with remaining toffee chips and bake an additional 5 minutes.