Step 1

In a mixing bowl or the bowl of a stand mixer, cream together the butter and sugar. Add the egg and vanilla and mix until combined.

Step 2

Stir in the flour and salt until just combined.

Step 3

Wrap and refrigerate 2/3 of the dough. Add gel color, a little at a time, to the remaining dough and mix until the desired color is reached. Shape dough into a flattened round, wrap and freeze for at least an hour, until very cold and firm.

Step 4

Roll out the colored dough to a 1/2" thickness. Cut out shapes with a mini cookie cutter and assemble in a stack. If the dough starts to warm and soften at any point, freeze for 15 minutes before continuing. Freeze the stack of cutouts for 15 minutes or until very firm. Meanwhile, take out the uncolored dough to soften.

Step 5

Cut or roll out long strips of uncolored dough to wedge into the crevices of the cut out stack. Then wrap the stack with remaining dough and roll into a log shape. Wrap and freeze until completely solid, at least four hours.

Step 6

Preheat oven to 350º F. Thaw frozen dough for 15 minutes and roll in sprinkles if desired. Slice 1/4" cookies and bake on parchment paper or a baking mat for 9-10 minutes, until just set.