First, make the crust. Combine the flour, sugar, and salt in a medium bowl. Cut the cold butter into small cubes and use a pastry blender or your clean hands to incorporate the butter into the flour mixture. It should look like small grains or pebbles. Then, add in 3 tablespoons of cold water and try to press the dough into a ball. If the mixture seems too crumbly to stay in a ball, then add another tablespoon of cold water. Once a dough ball forms, wrap in plastic wrap and refrigerate for at least an hour or up to three days. I usually make my pie crust a day or two ahead of time, so it feels like less work on the day I make the pie.
While that chills, you can make the horchata. First, I heated 2 cups of whole milk with 2 cinnamon sticks until very hot (but not boiling).Then, remove from heat and stir in 1/4 cup almond flour, 2 teaspoons vanilla extract, and 7 oz. sweetened condensed milk. Refrigerate for 30 minutes to an hour, then strain with a fine mesh strainer. This will make twice as much horchata as you need for this recipe, but it’s difficult to make such a small amount.
In a large mixing bowl, cream together the butter, sugar, and salt. Stir in the eggs one at a time, incorporating each well. Then whisk in the 1 cup of horchata and 2 tablespoons of flour. Roll out the pie crust and add to a pie pan that has been lightly buttered and dusted with flour. Poke a few holes in the crust with a fork. Then pour the batter in.
Bake at 400°F for 10 minutes, then reduce the heat to 350°F and continue to bake for 45-50 minutes. The pie will puff some by the time it’s done, but it will flatten back out as it cools. Allow to cool before trying to slice and serve. Enjoy!