Sopa Paraguaya is a culinary paradox. The legend says it originated in the 19th century when the cook of President Carlos Antonio López added too much cornmeal and milk to the traditional ground meat soup (Sopa Guasu). Instead of a soup, a dense casserole resulted. The President liked the new 'mistaken' dish so much that he ordered it to be served henceforth, naming it 'Paraguayan Soup'.
It is a moist, savory cornbread often baked using drippings from roasted meat. Queso Paraguay is the ideal cheese, but it can be substituted with a non-melting fresh cheese (e.g., feta, panela, or a mix of cottage and mozzarella).
Preheat the oven to 180 °C (350 °F). Grease a suitable baking dish (approx. 20x20 cm) with butter or oil.
Melt the butter/lard in a large skillet. Add the onion and a pinch of salt. Sauté the onion over medium heat until it softens and becomes translucent (about 5-8 minutes). Let it cool slightly.
In a large bowl, mix the cornmeal and salt. In another bowl, whisk the eggs with the milk.
Combine the dry and wet ingredients. Add the baking powder (if using).
Add the cooled onion and the grated or cubed cheese. Mix thoroughly until all ingredients are combined. The batter should be very thick and milky.
Pour the batter into the prepared dish and spread evenly.
Bake in the preheated oven for 40 to 50 minutes until the surface is golden brown and a toothpick comes out clean.
Let the Sopa Paraguaya cool for 10-15 minutes before slicing. Serve warm, ideally as a side dish to grilled meat (asado) or a stew.