To make a lemon poppy seed cake in the a slow cooker, first combine flour, cornmeal, baking powder, baking soda, and salt in a bowl and stir well.
Beat the butter and one-and-a-quarter cups of granulated sugar with an electric mixer on medium-high until smooth.
Add the eggs, and beat about 2 minutes or until fluffy. Add sour cream, vanilla, lemon zest, and poppy seeds, and beat to combine. Reduce the speed to low and slowly incorporate the flour mixture.
Place a 15-inch piece of parchment paper in the bowl of a slow cooker, letting the excess come up the sides. The parchment paper will help you lift the cake out of the slow cooker when it's done, but; it also creates a bit of aan attractive, rustic look for this the cake.
Transfer the batter into the bowl of the slow cooker.
Set the cooker to on HIGH and cook, covered, for 1 hour, then reduce to LOW and cook for 2 hours, or until set and a skewer inserted in the center comes out clean.
Combine the remaining granulated sugar and lemon juice in a bowl, stir well, and drizzle evenly over the top of the cake.
Holding Grasping the parchment paper, transfer the cake to a rack. , and Let let it cool for at least 15 minutes.
Because it was baked in a slow cooker, the cake will develop what is almost a crust layer on the bottom with an upper part that is extremely moist. Dust the finished cake with the confectioners' sugar and serve with the whipped cream. Because it was baked in a slow cooker, the cake develops somewhat of a crust layer on the bottom with an upper part that is extremely moist.