Preheat oven to 325 °F and grease a 9-inch square pan. Line pan with parchment so paper overhangs on two sides (this allows you to pull out squares easily for slicing).
For base, pulse digestive cookies in a food processor until a fine crumb. Toss with melted butter to combine and press into prepared pan. Sprinkle peanuts over base. Sprinkle chocolate chips over peanuts then top with toasted coconut. Pour condensed milk over coconut and spread gently. Bake for 325 °F for 55 to 65 minutes, until condensed milk is bubbling and a golden brown. Allow to cool completely (about 3 hours) before slicing.
Store Gooey Southern Squares in an airtight container for up to a week.
Prepare Gooey Southern Squares as above, except prepare a 9-inch round springform pan and replace peanuts with Macadamia nuts. Drizzle melted dark chocolate over tart and cut into wedges to serve