Preheat the oven to 350°F (180°C). Line a baking tray with parchment paper.
Cream the butter and sugar in a large bowl until light and fluffy.
Add the egg yolks and vanilla. Mix well until smooth.
In another bowl, mix flour, salt, and baking powder. Slowly add this to the wet mixture and stir until the dough forms.
Scoop small balls of dough and roll each one in the oats.
Place them on the tray, leaving space between each.
Press half a cherry on top if using.
Bake for 15–18 minutes until the edges turn light golden.
Let the cookies cool on the tray for 5 minutes, then move to a rack to cool fully.