Prepare the Dough
In a bowl, mix warm water, sugar, and dry yeast. Let it sit for 10 minutes until foamy.
Add flour, salt, olive oil, and egg. Knead into a smooth dough. Cover and let rise for about 1 hour or until doubled in size.
Caramelize the Onions
Heat a pan over medium heat with a drizzle of olive oil.
Add sliced onions and cook slowly, stirring occasionally, until caramelized and golden brown (about 15-20 minutes).
Mix in black pepper, paprika, and dried thyme. Set aside to cool.
Assemble the Onion Cake
Preheat the oven to 180°C (350°F).
Roll out the dough into a rectangular or circular shape and place it on a lined baking sheet.
Spread sour cream evenly over the dough, then top with caramelized onions and grated cheese.
Bake to Perfection
Bake for 25-30 minutes, until the crust is golden and the cheese is melted and bubbly.
Let cool slightly before slicing and serving.