Combine warm water, sugar, and yeast in a mixing bowl; let bloom for 5 minutes. In another bowl, mix flour and salt. Add yeast mixture and olive oil, knead until smooth (8-10 minutes), then let rise for 1 hour.

Heat olive oil in a skillet, sauté sliced onion on low until caramelized (about 20 minutes). Add spinach and garlic, cook until wilted. Stir in nutritional yeast and let cool.

Preheat oven to 375°F (190°C). Roll out dough to a rectangle. Spread filling on dough, roll into a log, and cut into 10–12 rolls. Place seam-side down in a greased baking dish.

Cover rolls with a towel, let rise for 20 minutes. Bake in oven for 25-30 minutes until golden brown.

Cool slightly before serving. Enjoy warm with marinara sauce for dipping.