Preheat the oven to 300°F (150°C). Line a baking sheet with parchment paper.
Process the florets in a food processor until completely chopped into meal. Transfer the meal to a clean, thin dish towel or piece of cheesecloth and, working over the sink, squeeze out all the excess liquid.
Place the squeezed meal back in the food processor along with the Parmesan, tapioca flour, egg, and egg yolk. Process until the mixture is well combined and looks like a mash.
Transfer the mixture to a plastic bag and cut off one corner to create a ½-inch (1 cm) opening. On the prepared baking sheet, pipe the gnocchi into pieces about 1 inch (3 cm) long and ½ inch (1 cm) to ¾ inch (2 cm) wide. The gnocchi won’t spread too much while they cook, so you can line them up closely, about an inch (3 cm) apart.
Once all the gnocchi are piped, use your fingers to shape them gently into ovals. Then gently press the tops with a fork to get that traditional “lined” look. Bake for 30 minutes.
When the gnocchi are done, make the sauce: Heat the butter over medium-high heat in a pan large enough to hold the gnocchi. Add the garlic, sage, and chives. Cook for 2 minutes, until fragrant.
Add the baked gnocchi to the pan and toss a couple times until they are coated with the butter sauce. Add the ¼ cup Parmesan and cook for 1 minute more, allowing the cheese to melt and become integrated into the gnocchi.