With a shortbread base, a layer of chocolate and a rich, walnut-studded filling, these Derby Pie Shortbread Bars will soon become one of your favorite sweet treats.
Line a 13 x 9-inch pan (preferably metal) with foil. If necessary for full coverage, use one long piece for the 13-inch length and another shorter one for the 9-inch width of the pan, placing them in a cross pattern. Let the long piece of foil hang over the short sides of the pan by about 2 inches for easy removal of the bars once they have cooled. Lightly grease the pan (especially the sides) with either nonstick cooking oil spray or melted butter.
Melt the butter and let it cool slightly to just warm. Mix the butter, sugar, and salt in a medium-size bowl until combined.
Whisk the flour and cornstarch together. Then, add them to the mixture and stir until combined.
Press the shortbread base dough into the prepared pan evenly all around, prick it with a fork, and refrigerate it for at least 20 minutes.
While the dough is chilling, preheat the oven to 350 degrees F. Bake the crust on the middle rack for about 20 minutes, just until the edges begin to brown.
About 15 minutes into the baking time for the dough, mix the butter, brown sugar, honey and heavy cream in a medium-size saucepan or pot. Stir occasionally and let it simmer for about 1-2 minutes. Stir in the chopped walnuts and take the filling off the heat.
As soon as the base is finished baking, take it out of the oven, sprinkle the chopped chocolate over it.
Gently smooth out the chocolate with a knife or heat-resistant spatula. If the chocolate does not completely melt right away, put the base with the chocolate pieces back in the oven for just a minute, then remove it and continue smoothing out the chocolate until it is an even layer.
Dot teaspoonfuls of the still-warm walnut filling over the chocolate, gently spread it out evenly, and bake the bars for about 20 minutes, just until the center is set. If desired, grind walnuts over the top either before or after baking - or both if you're a fan of the look and taste of the "walnut snow."
Let the uncut pan of base, chocolate, and walnut filling completely cool in the pan before removing it from the pan by flipping the pan over onto one cutting board, then putting another cutting board on top and flipping it right side up. and cutting them. You can either pull off the foil before putting the second cutting board on top or leave it on and gently lift the bars off the foil with a thin spatula after you cut them.
An small offset metal spatula works well for smoothing out the chocolate layer and afterwards, for smoothing out the walnut mixture over the chocolate. If you do not have one, use a butter knife or other knife with a flat (i.e.not-sharp) blade.
The walnut filling hardens quickly and can be difficult to spread out as it cools, so leave it to stay warm on the stove until the chocolate layer is done, then dot it on the chocolate in small amounts - teaspoonfuls if possible.
These bars are rich. Therefore, I prefer to cut them small. I cut the 13 x 9-inch pan into 48 squares each 1 & 1/2-inches. Whether you make them that size, or go for larger pieces, use a large knife or cleaver to cut. It is best to begin by cutting at the mid-point of the side, then cut each half into halves or thirds and proceed in that manner to make the pieces as small as you wish. For 48 squares from a 13 x 9-inch pan, you cut the short side into half then each half into thirds, and the long side into half, then quarters - or 6 cuts on the short side and 8 on the long side.