1. Preheat the oven to 180°C (350°F).
2. Melt the butter in a saucepan.
3. Gradually add the flour and mix with a wooden spoon.
4. Gradually pour in the milk while whisking.
5. Bring the béchamel sauce to a boil, stirring until the mixture thickens.
6. Season with salt and pepper, and mix off the heat until smooth.
7. Slice the beets very thinly using a knife or mandoline.
8. Arrange beet slices at the bottom of a baking dish.
9. Layer with lasagna noodles, beets, ground meat, béchamel sauce, lasagna noodles, and béchamel sauce. Sprinkle with Parmesan cheese.
10. Bake the beet lasagna for 25 minutes. Serve hot.