Line a 9-by 9-inch baking pan with aluminum foil, allowing some extra at each end.
Grease and flour the foil.
Toast the almond pieces in a frying pan over medium-low heat, stirring frequently, until they begin to color and become fragrant, about 7 minutes.
Pour them out of the pan and set aside.
Chop the toffee bars into 1/2-inch pieces (if using snack-size bars, chop them in half).
Sift together the flour, baking powder and salt.
In the large bowl of an electric mixer, combine the melted butter and brown sugar, breaking up any hard lumps of brown sugar.
Beat in the egg, vanilla and almond extract.
Beat in the flour mixture.
Combine the toasted almonds, chopped toffee bars and chocolate chips, mixing well, then stir the mixture into the batter, stirring to coat all the mix-ins.
Scrape the batter into the prepared pan and spread it evenly.
Bake about 40 minutes (about 5 minutes longer in an 8-by 8-inch pan), until a toothpick inserted near the center comes out clean.
(If the toothpick comes out covered with chocolate, it hit a chocolate chip; try somewhere else.) A toothpick might come out apparently clean after about 30 minutes, but close examination would indicate it's wet.
Some people might like the bars that way; they're certainly gooey, but they really aren't done.
Cool at least an hour in the pan, lift out by the edges of the foil, peel away the foil (invert if necessary) and cut into serving pieces.