Combine the butter, sugar, and flour until well mixed and then add the egg, forming a crumbly mixture. Press into a well oiled 9 X 13 pan and set aside.
Mix all the custard ingredients together, beating until completely combined.
Slice the peaches and arrange evenly over the top of the crust. Pour the custard over the fruit, making sure all peices are covered.
Bake at 400 degrees for 10 minutes and then reduce heat to 350 and bake an additional 25 to 35 minutes. Test for doneness by inserting a knife into the custard; if it "comes out clean" (i.e., the knife blade won't have any custard clinging to it), it will be done.
Notes
Also may use fresh nectarines, raspberries, strawberries, apricots or other fruits.