In a mixing bowl, whisk the egg with an electric whisk for about 1 minute until slightly frothy.
Add the ricotta, grated Parmesan and a pinch of salt, then whisk just until the mixture is smooth.
Evenly sprinkle the coconut flour, xanthan gum and psyllium husk powder over the mixture; whisk to combine, then fold with a spatula until a soft dough forms.
Chill the dough in the refrigerator for 1 hour (or freeze about 15 minutes) until firmer; you can also refrigerate covered overnight.
Divide the dough into four pieces, oil your hands lightly, roll each into a thin log and cut into 1–1.5 inch (2.5–4 cm) pieces.
If using a gnocchi board, gently press and roll each piece to form ridges; if using a fork, roll into a ball and press with the tines to create grooves.
Place the formed gnocchi on a parchment-lined baking tray and freeze for about 20 minutes until firm but not rock solid.
Heat the butter in a frying pan over medium heat. Add the gnocchi and minced garlic and fry the gnocchi on one side for about 1.5 minutes.
Carefully turn each gnocchi, add the sage leaves, and cook another 1.5 minutes until golden on both sides; season with salt and cracked black pepper to taste.
Serve immediately.