Preheat your oven to 350°F. Coat the bottom and sides of a 9×13-inch baking pan with butter or a nonstick cooking spray, then line the bottom with parchment paper, extending the lengths up two sides.

Stir together rhubarb, lemon juice and ⅔ cup sugar and set aside.

Beat butter, remaining sugar and lemon zest with an electric mixer until light and fluffy.

Add eggs, one at a time, scraping down the sides after each addition.

Whisk together flour, baking powder, ¾ teaspoon table salt and ground ginger in a small bowl.

Add one-third of this mixture to the batter, mixing until just combined.

Continue, adding half the sour cream, the second third of the flour mixture, the remaining sour cream, and then the remaining flour mixture, mixing between each addition until just combined.

Dollop batter over prepared pan, then use a spatula to spread the cake into an even, thin layer.

Pour the rhubarb mixture over the cake, spreading it into an even layer.

Stir together the crumb mixture, whisking the flour, brown sugar, table salt and cinnamon together, then stirring in the melted butter.

Scatter crumb mixture evenly over rhubarb layer.

Bake cake in preheated oven for 50 to 60 minutes until a tester comes out free of wet cake batter below and it is golden on top.

Cool completely in the pan on a rack.

Cut the two exposed sides of the cake free of the pan, then use the parchment 'sling' to remove the cake from the pan.

Cut into 2-inch squares and enjoy.