Preheat oven to 350 degrees F.
Prepare Peach Topping (see below).
In a large bowl, combine flour, sugar, baking powder, and salt. Add egg, milk, and vegetable shortening; beat 2 minutes. Add lemon zest, lemon juice, and vanilla extract; beat 2 minutes. Pour cake batter over prepared Peach Topping, spreading evenly with a spatula to reach the sides of the pan.
Remove cake from oven. Let cake cool, on a rack, for 10 minutes.
Run knife around edge of pan to loosen; cover with a cake plate and invert. Gently remove the cake pan (be careful, as the fruit and topping is still quite hot and will burn).
Serve warm. Also delicious served with whipped cream or vanilla ice cream.
In a 10-inch cast iron frying pan or a 9x2-inch cake pan over low heat, melt butter. Stir in brown sugar until well blended. Remove from heat.
Arrange peach slices in a layered circular pattern on top of sugar mixture until bottom of pan is fully covered. Sprinkle with chopped nuts.
Set aside until ready to pour the prepared cake batter on top.
* To slice peaches, carefully cut the peaches in half from top to bottom and gently twist them to separate the halves from the pit. Remove the pit. Lay the peaches halves flat on a cutting board and slice into wedges about 1/4-inch thick.
Peach Upside Down Cake Recipe: https://whatscookingamerica.net/cake/peach-upsidedowncake.htm