Preparation

• Combine 1 cup of the sugar and 1 cup water in a 2-quart saucepan. Bring to a simmer over medium heat, stirring frequently to dissolve the sugar, about 2 minutes. Add the chiles and simmer for 5 minutes. Strain through a medium-mesh strainer over a bowl and set aside. (Reserve the syrup for another use, such as the Spicy Bourbon Sidecar, if you like.) When cool, finely chop the chiles.
• Position a rack in the lower third of the oven and heat the oven to 350°F. Butter the bottom and sides of an 8- or 9-inch round cake pan, line the bottom with a parchment round, and butter the parchment. Sprinkle 1/2 cup of the pepitas evenly over the bottom of the pan, and then sprinkle with 2 Tbs. of the sugar. Set aside.
• Combine the remaining 1-1/4 cups pepitas and the remaining 1 cup sugar in a food processor. Pulse until the pepitas are pulverized and resemble damp sand. Add the eggs and butter, and pulse until the mixture is well-combined. Add the flour, tequila, and baking powder and pulse until the mixture is just combined. Add the chocolate and pulse until combined. Add the ancho chiles and pulse until combined.
• Scrape the batter into the prepared pan and bake until a toothpick inserted into the center comes out clean, 35 to 40 minutes for a 9-inch pan and 45 to 50 minutes for an 8-inch pan. Let the cake cool in the pan for 10 minutes, then invert onto a platter and remove the parchment. Let cool until just warm or room temperature, then slice with a serrated knife to serve. The cake will keep, tightly wrapped, at room temperature for up to 3 days.