Preheat the oven to 325 (F).
In a medium bowl, using your fingers, rub together 1/3 cup sugar and 1 tablespoon lemon zest. This helps release lemon oil from the zest.
Whisk in 4 eggs, and then add 1/2 cup almond flour, 1 cup Greek yogurt, 1 cup coconut milk, and 1/4 cup lemon juice. Whisk until smooth.
Place ramekins in a deep-rimmed baking pan. Pour the custard into the ramekins. Bring the baking pan to the oven and set it on the rack. Pour hot water into the baking pan, enough to come halfway up the sides of the ramekins. Bake in the water bath for 30 minutes, or until set.
Remove the baking pan from the oven and carefully lift out the ramekins. Let them cool to room temperature on a cooling rack and then transfer them to the refrigerator. Serve chilled with 1/4 cup toasted almonds.