Bring a pot of water to a rapid boil and blanch the kumquats for 1 minute and then transfer them to an ice bath to cool. This step helps maintain that vibrant orange color.
In a large pot, bring the water and sugar to a simmer. When the sugar is fully dissolved, add the kumquat slices and simmer for 20-30 minutes, until the rinds are translucent.
Remove the kumquat slices and let cool completely on a wire rack.
Save the simple syrup for cocktails!
Tart Crust
Preheat your oven to 350°F.
Pulse the petit beurre in a food processor until you have about 1 ½ cups of crumbs.
In a large bowl, combine the cookie crumbs, almond flour, granulated sugar, and melted butter. Mix until it resembles wet sand.
Press the mixture into the bottom of the tart pan and slightly up the sides. Make sure it is tight and compact! You can use the bottom of a flat measuring cup to help pack down the crust.
Bake the crust at 350°F for about 15 minutes or until it's lightly golden brown and looks dried out.
Let cool to room temperature before filling.
Custard Filling
In a small bowl, beat the egg yolks until smooth and set aside.
Scald the milk in the microwave or on the stove top until it is almost boiling. (I prefer the microwave because there is no chance of burning the milk).
In a large sauce pan, combine the flour, sugar, and salt.
Over medium-low heat, slowly add in the milk about ½ cup at a time while whisking constantly.
As the filling begins to thicken, add in another ½ cup of milk and continue whisking.
Once all of the milk is added and the filling has thickened (enough the coat the back of a spoon), remove the pot from the heat.
Pour about ½ cup of the filling into a glass measuring cup and then slowly drizzle it into the beaten egg yolks, whisking constantly until fully combined and smooth.
Pour the egg mixture back into the pot with the rest of the filling cook for an additional 2-3 minutes or until the filling has thickened to a pudding consistency.
Stir in the butter and vanilla extract until smooth. Add in 1-2 tablespoons of the leftover kumqat simple syrup if desired!
Pour the custard through a fine mesh strainer to remove any lumps.
Cool the filling almost to room temperature, stirring occasionally, before pouring into your cooled tart shell. Cover and chill in the fridge overnight (at least 3 hours) to let the filling set.
Top with candied kumquats and enjoy!
Store the tarts covered in the fridge for up to 3 days!
Notes
The most important step in making the custard is tempering the eggs. I know that sounds scary, but I promise it's not that hard! Tempering just means that you'll slowly add a small amount of hot liquid to the beaten eggs so that the temperature rises slowly and they don't scramble (trust me, you don't want scrambled eggs in your custard!Once the filling mixture is scalding hot, you'll remove about ¼ cup and place it into a glass measuring cup (the best for pouring hot liquid) and then slowly drizzle the syrup into the beaten eggs while whisking. Then you'll add the warm egg mixture back into the rest of the custard. Easy peasy!This recipe can be used to make a few different sizes of tart!