Instructions

1. First, make the strawberry rhubarb jam. In a saucepan over medium heat, combine the chopped rhubarb, sugar, and cornstarch. Cook the mixture over medium-low heat, stirring constantly with a silicone spatula, until the rhubarb is starting to break down and become jammy, about 5 minutes (this gives the rhubarb a head start because it breaks down slower than the strawberries!). Add the strawberries and continue to cook, stirring as needed until the mixture is thick and jammy, about 8 more minutes. Remove the pan from the heat and set aside to cool
2. Next, make the crumble. Preheat the oven to 350°F. Line a 9 x 13-inch baking pan with parchment paper on all sides. Set aside.
3. In a stand mixer fitted with the paddle attachment, add the butter and sugar. Beat on medium low speed just until combined. Add the egg, vanilla extract and orange zest and beat until combined. Add the flour, baking powder, and salt granulated sugar and beat on medium-low speed until the mixture forms a thick, crumbly dough, about 1 minute.
4. Transfer 2/3 of the dough to the prepared pan and use the bottom of a measuring cup to pat it into an even layer to form the crust. Top the crust with strawberry rhubarb jam, using a rubber spatula to spread the jam evenly to the edges of the pan. Squeeze the remaining 1/3 of the crumble mixture into your palm, then break it apart into big and small clusters, sprinkling them all over the jam.
5. Bake until the jam is starting to bubble at the edges and the top of the bars are light golden brown all over, 25 to 30 minutes. Allow the the bars to cool completely before slicing and serving!