In a quart-sized glass jar, lightly pack the brown sugar into the bottom. Sprinkle the chocolate chips into an even layer over the brown sugar. Spoon in the flour gradually and smooth into an even layer. Add the baking powder and salt. Add the pecans or walnuts on top. Finally add the toffee bits. Fasten a lid and ring to the jar. Attach the following instructions.
To make the blondies, in a medium bowl, whisk together 2 large eggs, 4 tablespoons melted butter and 1 teaspoon vanilla extract. Add the contents of the jar and mix well.
Lightly grease an 8X8-inch baking pan and spread the batter evenly. Bake at 350 degrees for 25-30 minutes until baked through (don't overbake!).
Nuts: I know someone will probably ask: can you make these without nuts? Sure! But obviously your jar will be less full. You could try adding more toffee bits or chocolate chips to make up the space or just leave it with a little space at the top.