Gingersnap Peach Upside-Down Cake

Line the slow cooker with a large sheet of parchment paper, letting the ends reach over the rim, and pushing the paper firmly into the bottom of the slow cooker insert. Generously spray the parchment paper with cooking spray.
In a large bowl, combine the peaches and crystallized ginger. Set aside.
In a small saucepan on the stovetop over medium heat, melt 1/4 cup of the butter. Stir in the brown sugar. Pour this mixture into the slow cooker and spread evenly over the bottom. Next, spoon the peach and crystallized ginger mixture over the butter mixture. Do not stir. Then sprinkle with the gingersnap cookie crumbs.
Use a hand-held mixer to cream together the white sugar, shortening, and the remaining 2 tablespoons of softened butter in a bowl. Add the egg, egg yolk, and vanilla and mix in. In a separate bowl, combine the flour, baking powder, and salt. Alternate adding the flour mixture and the half-and-half to the creamed sugar mixture. Mix well and spoon on top of the gingersnap layer, spreading the mixture a bit, but not mixing it. Everything should be layered.
Place several layers of paper towels over the slow cooker and replace the lid. Turn the slow cooker to high and cook for 1 1/2 to 2 hours, until a knife inserted into the middle comes out clean.
Remove the lid from the slow cooker and cook an additional 15 to 20 minutes for the top to form a crust.
Lift the cake from the slow cooker using the long ends of the parchment paper and place on a large dinner plate. Place a second dinner plate on top. Holding both plates, carefully flip it over and remove the parchment paper. Slice the cake and serve topped with freshly whipped cream or vanilla ice cream.