Proja sa Blitvom/Savory Cornbread with Swiss Chard

Name: Proja sa Blitvom/Savory Cornbread with Swiss Chard
Prep time: 10 min
Cook time: 35 min
Total time: 45 min
Cuisine: European, Mediterranean, Greek
Ingredients: 1 bunch Swiss Chard or Spinach, leaves only (if using Chard), chopped - around 4 cups/150g; 3 eggs; 1 1/4 cup (300 ml) sparkling water; 1/2 cup (100 ml) oil; 1/2 cup (100 ml) Kefir; 3 heaping tablespoons Greek Yogurt (3 dobre kašike); 1 teaspoon (6 g) salt; 2 cups (200 g) cornmeal (I use Yumis brand); 1 cup (100 g) all purpose flour; 1 tablespoon (15 g) baking powder; 1 cup (150 g) crumbled feta cheese