Recipe adapted from Kenden's blog Jewish Food Hero. 

• Preheat oven to 170°C.
• To make the cake batter, first prepare the dry ingredients by whisking together the matzo meal, potato starch, baking powder, and salt in a medium bowl. Set aside
• Next, prepare the wet ingredients by combining the applesauce, summer squash, sugar, orange juice, flax “egg,” and water in a larger bowl. Stir to combine and set aside
• Add the dry mixture to the wet, stirring to combine until you have a smooth batter
• Next make the cinnamon sugar mixture by mixing together the cinnamon, nutmeg, and sugar
• Pour half the cake batter into a lightly oiled cake pan or springform pan and top with half the prepared apple slices. 
• Sprinkle with half the cinnamon sugar mixture then spread the remaining cake batter on top
• Arrange the remaining apple slices in a pretty pattern on top of the cake and sprinkle with the remaining cinnamon sugar mixture and the chopped pistachios.
• Bake for 40 minutes.
• Serve warm or cool either as is, or with a scoop of non-dairy vanilla ice cream (if serving hot), or with a sprinkling of icing sugar if serving cool.