Preheat the oven to 325°F (160°C). Line a baking sheet with parchment paper or a Silpat.
Place the cashew butter in a large microwave-safe bowl and warm until smooth and creamy, about 1 minute; stir to combine.
Add the honey and butter extract to the bowl and beat with an electric hand mixer until fully combined and smooth.
Beat in the egg until the mixture is uniform.
Stir in the vanilla whey protein powder, baking soda, and a pinch of salt until a sticky, wet dough forms.
Pour the sprinkles onto a small shallow plate. Using about 1 tablespoon of dough per cookie, roll into balls.
Roll each ball lightly on the top and sides in the sprinkles so only the outside is coated, then place sprinkle-side up on the prepared baking sheet.
Flatten each cookie to about 1/3 inch thickness. Bake for 12–13 minutes, until the tops feel just set and the cookies have risen slightly.
Let the cookies cool completely on the baking sheet before serving.