In a stand mixer (or large bowl with a hand mixer), use the paddle attachment to beat the softened butter, sugar, and Jell-o mixture together on medium speed until well combined, about 3-4 minutes.
Scrape down the sides of the bowl and add the egg, baking powder, and vanilla extract. Mix again on medium speed for 3 minutes until well combined.
Scrape down the sides of the bowl again and add the flour and salt. Beat on low speed until everything is just combined. It will be crumbly and look a little dry but will stick together if you squeeze it in your hand. If it does not stick together, add a very small amount of water and briefly mix until it does stick together.
Remove from the mixer and make sure all of the dry ingredients on the bottom are incorporated.Squeeze a small handful of the dough together. If the dough is not squeezing together well and feels too dry, add a tablespoon of water and briefly mix to incorporate, then check again. The dough should hold together but not be too dry where it does not hold together. You do not want too much moisture because a wet dough will cause it to puff and lose shape in the oven.
Line a baking sheet with a silicone baking mat or parchment paper.
Scoop the dough out with a size 40 scoop (or 1.5 Tablespoons of dough). Squeeze the dough together several times in your hands to make sure it is well incorporated. Roll the dough into a ball.
Place the ball on the baking sheet where you want the cookie to be (they are very difficult to move after cutting). Using a sharp knife, cut down into the ball almost all the way through (if it cuts all the way through, that is fine). Repeat the cut two more times on the ball, evenly spaced, making six segments.
Gently pull each petal down toward the baking sheet. It does not have to lay flat as it will fall further when baking. If the base comes apart, it is fine, just simply place the petals as close together in the center as possible. When it bakes, it will close the gap.
Place several of your yellow sprinkles in the center of the flower.
Repeat with additional dough until the baking sheet is full (9-12 flowers).
Freeze the cookies on the baking sheet for 10 minutes.This helps them keep their shape.
Preheat oven to 350°F.
When the oven is hot and the cookies have chilled, bake the cookies for 12 minutes until set and barely turning a light brown on the bottom edges. You almost want them to seem a little undercooked to get soft cookies.
Remove from the oven and let sit on the baking sheet for 5 minutes to firm up a little. If needed, add additional yellow sprinkles immediately after removing from the oven (sometimes they get sucked down under the cookie).Remove from the baking sheet to finish cooling on a cooling rack.
Repeat the process with the remaining dough, making additional batches as others are chilling and baking.If your dough is becoming too dry as you go, add a very small amount of water as needed.
If you are constantly working new batches while cookies are chilling and cooking, it will be faster than if you do one tray start to finish before starting another.