Preheat the oven to 350 degrees and place parchment paper on top of two baking sheets.
Cream together the butter and sugar in a bowl attached to a stand mixer until it is light and fluffy. About 3 minutes.
Add in the bourbon and salt and mix until combined.
Add in the flour and mix on low until it all comes together.
Place about 1/4 of the dough in a piping bag fitted with a large rose tip. Twist the end so that the dough is pushed towards the tip. Set the bag on the warm oven for a minute to warm it up slightly. Once warm, pipe the dough into tight swirls on the parchment. They shouldn't spread while baking so you can place them pretty close together. Repeat with the remaining dough.
Freeze the cookies on the tray until frozen. About 30 minutes.
Bake from frozen until the edges are just slightly browned. About 23 minutes.
Notes
Do not over mix the dough; this will make the cookies tough. Mix until everything just comes together.
If the dough is too stiff to pipe, let it rest in a piping back on the heating oven, which will loosen it up and make it more pliable.
Freeze the piped cookies. This is what keeps that rosette shape; if you bake without freezing, they will lose their shape.