I posted a picture of these bar cookies and then I realized that I did not include a recipe. This is an old recipe that is just about everywhere, but I thought I would post it anyway, along with some tips.
Not sure where these originated, my mom has been making them forever, but there is a version of this in the Silver Palate Cookbook.
8 ounces (1 cup) butter or margarine (the recipe has no salt, so Earth Best Margarine would probably be fine)
6.5 ounces (1 cup) brown sugar
1 egg yolk
1 tsp. vanilla
9 ounces (2 cups) all-purpose flour
14 ounces milk chocolate or 12 ounce bag of chocolate chips (I used Trader Joe’s)
1 cup chopped pecans or walnuts (I prefer pecans because they are sweeter and less bitter than walnuts, but both are good)
Cream the butter and sugar well. The mixture should lighten. If the mixture is still dark, keep beating. When in doubt, keep beating. Then add the vanilla and egg yolk. Fold in the flour by hand with a spatula. The mixture will be very soft and sticky.
Prepare your pan. You can use a 9″x13″ pan or a 10″x15″ pan. I used a 9″x13″ above, but it is a true 9″x13″. Those disposable tins are really more like 8″x12″. I lined the pan with parchment that I carefully folded to come up the sides of the pan. This gives you a way of lifting the bars out of the pan when the chocolate is still soft without messing up the chocolate or the nuts. It helps with the cutting of the bars, too. The only tricky thing is that the paper slip slides a bit when you are trying to spread the dough onto it. Chilling the dough to make it less sticky might have helped, but I was impatient and I just floured my hands and the surface of the dough and carefully eased it over the surface of the paper to evenly cover the bottom of the pan. I think I also might have temporarily taped the edges of the paper to the pan to keep it in place. This seems a bit fiddly, but you will be grateful when it comes to taking the bars out of the pan.
Once you have the dough evenly spread over the bottom of the pan, bake the dough at 350 degrees for 20-25 minutes, until it is lightly golden.
Take the pan out of the oven and evenly cover it with the milk chocolate bars or chocolate chips. The original recipes says to put it back in the oven, but I find that the residual heat from the baked crust is enough to melt the chocolate. When the chocolate starts to look shiny, it is melted and you can use an offset spatula to spread the chocolate in a thin layer (and if you don’t have an offset spatula, a knife will do, but really everyone who likes to bake should have an offset spatula).
Once the chocolate is nicely spread, sprinkle over the chopped nuts. I have found that fine bits of chopped nuts make an unattractive dust on the bars. Try to sift out the fine nut dust and just use the small to medium sized bits. Let the bars cool in the pan. The time to cut the bars is when the bars are cool and the chocolate is staring to set up, but before it has gotten really hard. When the chocolate looks dull and is as hard as clay, that is the right moment to cut the bars. Lift the bars out by pulling on the paper and place them on a cutting surface. Use a long serrated bread knife to cut the bars into 24 2″ squares, or 30 bars 1 1/2″ x 2 1/2″.
Note: these are heavenly with butter, milk chocolate, and pecans, but dairy-free with margarine and dark chocolate is lovely, too.