Ingredients
Crust:
1 cup butter, cut into small pieces
2 cups flour
2 Tbsp sugar
Custard:
6 egg yolks (save the whites for the topping)
2 cups sugar
¼ cup flour
1 cup whipping cream
1 tsp salt
5 cups rhubarb (approximately 6 large stalks, or 2 lbs.). Trim ends and slice into ½” pieces.
(Note: Substitute 1-2 cups of fresh, sliced Lepp’s strawberries for rhubarb to make an even-more delicious square.)
Meringue Topping:
6 egg whites, room temperature (see note)
½ tsp cream of tartar
½ cup sugar
1 tsp vanilla extract
½ cup unsweetened coconut (optional)
Instructions
Preheat oven to 350 degrees. Grease a 9 x 13-inch pan or line with parchment paper. In a food processor bowl, add flour, sugar and cubed butter. Pulse until butter is the size of peas. Alternatively, combine flour and sugar in a large bowl and cut in butter with hands or a pastry blender until crumbly. Press into greased pan. Place the pan on a larger baking sheet to prevent the crust from getting too dark. Bake in preheated oven for 20 minutes.
While crust is baking, prepare the filling. Separate eggs into yolks and whites, putting each into separate clean, large bowls.
Whisk egg yolks until mixed. In a small bowl, whisk sugar, flour and salt until combined. Add to egg yolks along with the cream and mix well.
Once crust is baked, scatter rhubarb, and strawberries if using, over the hot crust. Pour filling over the sliced fruit to cover it evenly. Return to oven and bake for 50-60 minutes, until filling is set and turning brown around the edges.
Shortly before the baking time is complete, whip egg whites and Cream of Tarter until soft peaks form. Slowly beat in sugar, ¼ cup at a time until peaks are stiff and glossy. Beat in vanilla.
Remove baking sheet from oven and immediately spread beaten egg whites over hot filling. Create some peaks and valleys in the topping by swirling with the back of the spoon. Sprinkle coconut over top.
Bake for an additional 12-15 minutes until golden brown.
Cool on a wire rack and refrigerate for 1-2 hours before serving.
Notes
How to achieve a fluffy and lofty meringue? The first rule is this: your bowl and whips must be spotless. The slightest trace of oil in the bowl or whips will compromise the result. Secondly, room-temperature egg whites are ideal. And finally, although Cream of Tartar is optional, it stabilizes the egg whites, and you’ll get the best results when you use it. (And btw, did you know that Cream of Tartar is an acidic byproduct of fermenting grapes into wine?)
To make the bars in an 8×8 pan, just halve the recipe.