Rompope

Pulse almonds with 2 tablespoons of the sugar in a food processor until ground to a fine paste. Bring milk, cinnamon, lemon rind, vanilla, and baking soda to a boil over medium-high heat in a large heavy-bottom saucepan. Reduce heat to medium-low and simmer for 15 to 20 minutes. Set aside. In a large bowl, whisk egg yolks, the remaining 1 1/2 cups sugar, and ground almonds until thick and pale. Remove cinnamon and lemon rind and discard. Whisking constantly, slowly add the milk to the yolk mixture. Return mixture to pan and cook over low heat, constantly stirring and scraping the bottom and sides of the pan, until the mixture thickens enough to coat the back of a spoon, 5 to 7 minutes. Set aside to cool completely, about 2 hours. Stir in rum or aguardiente. Serve.