For the cookies: Preheat the oven to 325 degrees F. Lightly butter 2 baking sheets.
Place the butter and sugar in the bowl of an electric mixer equipped with the paddle attachment-the one that looks like the peace sign-and beat until creamy and fluffy, 3 to 4 minutes. Add the egg yolks and almond extract and beat for another minute or so, scraping down the sides of the bowl occasionally.
In another large bowl, combine the flour, baking powder, baking soda, salt, and chopped almonds.
Gradually add the flour mixture to the butter-sugar mixture. When combined, the dough should be soft and homogeneous. Wrap the dough in plastic and refrigerate for at least 30 minutes, until firm.
When you're ready to bake, take the dough out of the fridge and roll it into 3/4-inch balls. Place the balls about 1 inch apart on a prepared baking sheet. Using the tip of your thumb, make a hole as deep as you can in each doughball without actually poking through the bottom. Roll your thumb around a little bit to widen the hole-this is your thumbprint!
Bake the cookies for 16 to 18 minutes or until they begin to turn golden around the edges. Remove from the oven and cool. While the cookies are cooling, repoke each one with your thumb to create a really nice spot for the caramel. Repeat with the remaining dough.
For the caramel: In a medium saute pan, combine the sugar, lemon juice, corn syrup, and 1/4 cup water. Bring the pan to medium-high heat. Be careful not to swish the pan around as that can cause the sugar to recrystallize. As the mixture boils, the water will evaporate and the sugar will begin to turn brown, or "caramelize." This is the point when you DO NOT want to take your eyes off it! Things can take a turn for the worse here and there will be no recovery. As the sugar begins to turn gold and move toward golden brown, remove it from the heat and add the heavy cream. As you do this it will bubble up like crazy. Be sure to use a pan large enough to accommodate the bubbling-this stuff is molten and can cause a very severe burn. Whisk the cream until things settle down and the bubbles subside, then add the butter 2 pats at a time, making sure each addition is thoroughly incorporated before adding more.
Let the caramel cool slightly, then spoon it into the hole of each cookie and let cool. You'll most likely have leftover caramel sauce, so save it for something yummy-like pouring over vanilla ice cream!
Flour acts differently depending on a whole bunch of factors-if your dough is a bit crumbly one day, add a few drops of water to pull it together.
Reprinted from Own Your Kitchen by Anne Burrell. Copyright (c) 2013 by Anne Burrell. Photographs copyright (c) 2013 by Quentin Bacon. Published by Clarkson Potter, a division of Random House, Inc.