8 ounces (about 3/4 cup) almond paste (not marzipan)
2 egg whites, lightly beaten in a small dish
1/3 cup granulated sugar
3 tablespoons almond meal or almond flour
~3/4 cup sliced almonds (they'll toast up in the oven, so no need to pre-toast)
2 tablespoons heavy cream
1 pat of butter
squirt corn syrup (optional, but makes for a nice gloss)
generous 1/4 cup chocolate chips or chopped chocolate
Line one baking sheet with parchment paper, or grease well and hope for the best. Set aside.
In a bowl or the bowl of a stand mixer, break almond paste into almond-sized chunks. Add sugar and 3 tablespoons of the beaten egg whites (reserving the remainder), and mix on medium-low speed until a smooth, sticky dough is formed, with no lumps. Add almond flour and mix until combined.
Whisk 1 tablespoon of water into the remaining tablespoon or so of egg whites, and set aside.
Pour the sliced almonds onto a shallow dish or plate. Take 1/6th of the dough, shape into a rough ball, and drop onto the plate sliced almonds. Roll, using the almonds to prevent the dough from sticking to your hands, into a 4-inch log. Transfer to a parchment-lined baking sheet, and gently shape into a crescent, pressing down to flatten slightly. Repeat with remaining dough.
Let cookies sit, uncovered, for 30 minutes, to dry out slightly. As they're drying, preheat your oven to 375° degrees Fahrenheit. When the cookies are ready, brush with the remaining egg white mixture. Bake for ~15 minutes, or until bottoms and almond edges are golden brown. Remove from the oven, and let cool on cookie sheet while you prepare the glaze (if the bottoms are too brown, you can transfer to a rack to cool — but be careful, as they're delicate while warm).
When the cookies are cooled, make the glaze. Place the cream, butter, corn syrup and chocolate in a dish, and melt on low in the microwave in 10-second bursts (alternately, melt carefully in a saucepan or, less carefully, a double boiler). Cool slightly, and dip half the cookies into the glaze (or sort of spoon it over the top). Return to the baking sheet, and let sit for 30 minutes until glaze is set (or longer, depending on the temperature — you can place in the refrigerator to speed the process). Enjoy immediately, or transfer to an airtight container or the freezer.