Heat the olive oil in a skillet over medium heat. Sauté the diced onion for 5 minutes, then add the garlic and cook for 1 minute.
Add the chopped spinach to the skillet and cook just until wilted. Remove from heat.
Mix the cooked quinoa, lentils, sautéed vegetables, nutritional yeast, paprika, oregano, salt, and pepper in a large bowl.
Blend one cup of the mixture with the vegetable broth in a food processor until it forms a paste, then fold it back into the main bowl to act as a binder.
Press the mixture firmly into a greased 8x8 inch baking dish. Bake at 375 degrees Fahrenheit for 25 to 30 minutes. Let rest for 10 minutes before slicing.