Ingredients:
Crust
1 cup all-purpose flour
¼ cup sugar
¼ tsp. salt
8 Tbsp. melted unsalted butter
½ tsp. vanilla extract

Filling
¾ pound rhubarb, washed and diced 
¼ cup maple syrup
4 each egg yolks
½ cup sugar
1 tsp. lemon zest
2 tsp. lemon juice
3 Tbsp. butter, diced

Make it:
For the crust

1. Preheat oven to 350 degrees.
2. Overturn an 8-inch pan on the table and wrap the outside securely with foil. Remove the foil and turn the pan over and press the foil into the pan, smoothing it as best as you can. Lightly butter or spray the foil with nonstick spray.
3. In a medium bowl, mix all of the crust ingredients in the order above, stirring just until smooth.
4. Pour the batter into the pan, and smooth it with a spatula or your hands so it’s as even as possible.
5. Bake the crust for 25 minutes, or until it is golden brown.

For the filling

1. Put the rhubarb and the maple syrup in a medium-sized saucepan over medium heat.
2. Stirring occasionally, let the mixture simmer and break down until the rhubarb has “melted” into a puree and most of the liquid has boiled off. Set aside.
3. Put the remaining ingredients in a medium-sized pot and stir with a whisk over medium-low heat until the sugar has dissolved and it starts to thicken (about 5 minutes). 
4. Add the rhubarb puree and cook for another 3 minutes over low heat, stirring constantly, making sure it doesn’t get too hot and burn!

To combine

1. Pour the filling mixture over the crust. Make sure to do this while both the crust and the filling are still hot.
2. Bake for 8 minutes, or until the rhubarb puree has just begun to set.
3. Let cool, cut into squares, and dust with confectioner’s sugar if you wish.

Notes: 
The bars will keep in an airtight container at room temperature up to three days. You can freeze the bars as well for up to one month, letting them return to room temperature before serving.

Rhubarb leaves are toxic to humans in large doses, so make sure to stick to the stalks!