01 - Whisk together flour and salt in a mixing bowl. Create a well in the center, then add eggs and half the milk. Whisk until smooth, then gradually incorporate remaining milk and melted butter. The batter should have a slightly runny consistency. Allow to rest for 10 minutes.
02 - Heat a non-stick skillet over medium heat and lightly brush with melted butter. Pour approximately ¼ cup batter into the skillet, swirling quickly to coat the bottom in a thin, even layer. Cook for 1–2 minutes until edges begin to lift and the bottom turns golden brown. Flip and cook for an additional minute. Transfer to a plate and repeat with remaining batter.
03 - Heat olive oil in a skillet over medium heat. Sauté the chopped onion until softened and translucent, approximately 3–4 minutes. Add sliced mushrooms and cook until golden brown, about 5 minutes. Stir in chopped spinach and cook just until wilted, about 2 minutes. Season generously with salt and pepper.
04 - Place 2 tablespoons of the vegetable filling and a sprinkle of grated cheese onto each crepe. Fold or roll the crepe neatly around the filling. Return filled crepes to the skillet and cook for 1–2 minutes per side until heated through and cheese is melted.
05 - Serve crepes immediately while hot. Garnish with fresh herbs such as parsley or chives if desired. Pairs well with a crisp white wine like Sauvignon Blanc.