1. In a medium saucepan, heat the butter over medium-low heat until melted.
2. Add the Gluten Free flour and whisk until smooth. Over medium heat, cook until the mixture turns a light, golden sandy color, for 7 minutes.
3. Pour in the warm milk to the flour mixture, whisking continuously until very smooth.
4. Bring to a boil. Cook for 10 minutes, stirring constantly, then remove from heat.
5. Season with salt and nutmeg, and set aside until ready to use.
6. Pour the sauce and tomato sauce over eggplant and bake add some cheese and lasagne is ready to serve.