Spinach and Ham Savory Crepe Cake

Name: Spinach and Ham Savory Crepe Cake
Ingredients: 2 tbsp butter; 2 onions (, chopped); 1/2 tsp salt; 2 280g box baby spinach; 3 tbsp butter; 2 tsp cornstarch or 4 tsp flour; 2 1/2 cups milk; 160 g Gruyere cheese; 1/2 tsp nutmeg; 1 tbsp salt; oil spray or olive oil; 1/2 cup rice flour; 1/2 cup quinoa flour; 1/4 cup tapioca starch; 1/4 cup potato flour; 5 large eggs; 1 cup coconut milk; 1 1/4 cup water; 3 cups cooked ham chopped into cubes; 2 cups Gruyere cheese (, grated); 1 crepe; 3 tbsp spinach mix; 1/4 cup ham; 3 tbsp béchamel sauce