Adapted excerpt from Maida Heatter's Brand-New Book of Great Cookies (Random House, 1995). Heatter found the original recipe for these brownies in a Palm Beach, Florida, newspaper. "It came from a local deli," she remembered. She tinkered with it and, in this version, added chocolate-covered mints. "I love the way they don't melt, but form a middle layer," she noted. "I love the simple black-and-white composition. They're just gorgeous!"
Preheat oven to 425°. Line a 9" × 13" × 2" pan as follows: Invert the pan and center a 17" length of aluminum foil, shiny side down, over the pan. With your hands, press down on the sides and corners of the foil to shape it to the pan. Remove the foil. Turn the pan right side up. Place the foil in the pan and very carefully press it into place in the pan. Now, to butter the foil, place a piece of butter (additional to that in ingredients) in the pan, and put the pan in the oven. When the butter is melted, use a pastry brush or a piece of crumbled plastic wrap to spread the butter all over the foil. Set the prepared pan aside.
Place the chocolate and the butter in the top of a large double boiler over hot water on moderate heat, or in a 4- to 6-cup heavy saucepan over low heat. Stir occasionally, until the chocolate and butter are melted. Stir to mix. Remove from heat and set aside.
In the large bowl of an electric mixer, beat the eggs, vanilla and almond extracts, salt, espresso powder, and sugar at high speed for 10 minutes. On low speed, add the chocolate mixture (which may still be warm) and beat only until mixed. Then add the flour and again beat on low speed only until mixed. Remove the bowl from the mixer. Stir in the walnuts.
Pour half the mixture (about 3½ cups) into the prepared pan and smooth the top. Place a layer of the mints, touching each other and the edges of the pan, all over the chocolate layer. Cut some mints to fill in large spaces on the edges. (You will not use all the mints. There will be some left over.) Pour the remaining chocolate mixture into the pan and smooth all over.
Bake for 35 minutes, reversing the pan front to back once during baking to ensure even baking. At the end of 35 minutes, the cake will have a firm crust on top, but if you insert a toothpick in the middle it will come out wet and covered with chocolate. Nevertheless, it is done. Do not bake any longer.
Remove the pan from the oven; let stand until cool. Cover the pan with a cookie sheet and invert the pan and the sheet. Remove the pan and the foil lining. Cover the cake with a length of wax paper and another cookie sheet and invert again, leaving the cake right side up. Now, the cake must be refrigerated for a few hours or overnight before it is cut into bars.
When you are ready to cut the cake, use a long, heavy knife with a sharp blade, either serrated or straight—try both. Cut the cake into quarters. Cut each quarter in half, cutting through the long sides. Finally, cut each piece into 4 bars, cutting through the long sides. (I think these brownies are better in narrow bar shapes than in squares.) Pack brownies in an airtight box or wrap individually in clear cellophane, wax paper, or foil. They freeze perfectly and can be served very cold or at room temperature.