In a large bowl, cream together the butter and sugar until light and fluffy using a stand mixer or electric mixer. Add in the eggs one at a time followed by the flour, almond powder, and baking powder, mixing until well combined.
Add the milk, vanilla extract, and lemon zest to the batter, stirring until everything is evenly incorporated.
Cut the rhubarb stalks in half lengthwise so they’ll fit in the pan. Butter the edges of the pan and place a circle of parchment paper in the bottom. Sprinkle some sugar over the parchment paper, add a few pieces of butter, then arrange the rhubarb stalks on the cake pan to create a nice pattern (see above how I created my pattern).
Cut the remaining rhubarb into small pieces and toss them with a spoonful of sugar until coated and add them to the cake batter.
Pour the batter over the rhubarb stalks.
Bake the cake in a preheated oven at 180°C (convection heat) for 35 minutes or until a toothpick inserted in the center comes out clean.
While the cake is baking, heat up some jam in the microwave or in a double boiler until it’s melted and smooth.
When the cake is done baking, remove it from the oven and while it’s still hot run a knife alongside the edges of the cake, place a serving plate and turn the cake over. Remove the parchment paper.
Brush the melted jam over the top of the rhubarb to enhance their color. Let the cake cool for a few minutes before serving. Enjoy with a chantilly or scoop of vanilla ice cream.