Combine warm water, olive oil, and sugar in a mixing bowl, then sprinkle yeast on top. Allow to activate for 5 minutes.

In another bowl, combine flour and salt. Gradually incorporate the yeast mixture to form a soft dough. Knead for 5-7 minutes until smooth and elastic.

Transfer dough to a greased bowl and cover with a damp cloth. Let rise in a warm spot for about 1 hour or until doubled in size.

Heat olive oil in a skillet over low heat. Add diced yellow onion and sauté for 20-25 minutes until caramelized.

Add minced garlic and fresh spinach to the skillet, cooking until spinach wilts. Remove from heat and let cool.

After rising, punch down the dough and roll out to 1/4 inch thick. Spread marinara sauce over the dough and distribute the filling.

Tightly roll the dough into a log shape, cut into 10-12 equal pieces and place in a greased baking dish.

Cover rolls with a towel and let rise for another 30-40 minutes.

Preheat oven to 375°F (190°C). Bake the rolls for 25-30 minutes until golden brown.

Let the rolls cool for a few minutes before serving warm or at room temperature.