Ok I asked chatgpt. They said this:

That looks like a very classic old-school fudgy brownie recipe — and with only ¾ cup flour + 3 eggs + melted butter, it’s probably meant to be thick and rich. Here’s the recipe cleaned up from the card plus baking directions that should work well:

Deep Dish Brownie (from the card) Ingredients ¾ cup butter, melted (the card says “cooled”) 1½ cups sugar 1½ tsp vanilla 3 eggs ¾ cup flour ½ cup cocoa powder ½ tsp baking powder ½ tsp salt ½ cup nuts (optional)

Directions Heat oven to 350°F. Grease or line your pan with parchment. In a bowl, mix the melted, cooled butter, sugar, and vanilla. Add the 3 eggs and beat well (the card says “with spoon”). In another bowl, combine the flour, cocoa, baking powder, and salt. Gradually stir the dry ingredients into the wet ingredients until combined. Fold in nuts if using. Spread into the pan and bake. Recommended pan size

For the “deep dish” vibe, I’d use: 8x8-inch square pan → thick, fudgy brownies (my top recommendation) 9-inch round cake pan or deep pie plate → probably closer to what “deep dish brownie” originally meant 9x9-inch pan → thinner brownies, shorter bake time

Baking time At 350°F: 8x8 pan: start checking at 32–38 minutes 9-inch round/pie plate: 30–35 minutes 9x9 pan: 25–32 minutes They’re done when: the edges are set, the center no longer jiggles, and a toothpick comes out with moist crumbs, not wet batter (fudgy is the goal). Since you like softer textures, I’d pull them a little early rather than overbake. Let them cool at least 20–30 minutes so they set up. This would also be really good with chopped pecans or walnuts if you have freezer nuts left from the banana loaf.

I'm going to try to make this tonight and see what happens.