Preheat oven to 400˚F (200˚C). Line a large baking sheet with parchment or lightly grease.
In a large bowl, combine the flour, sugar, baking powder, and salt.
Quickly cut in the butter using a dough blender, two forks, or your fingers until blended and no pieces are larger than a pea.
In a medium bowl, whisk together the Irish Cream, 1/2 cup (118 milliliters) of the heavy cream, egg, and vanilla extract. Pour into the dry ingredients and gently combine just until the mixture comes together. Do not overmix. If the mixture continues to fall apart, add a little more heavy cream.
Place the dough on floured surface and lightly knead to bring it together. Divide in half and press into two discs about 3/4 inches (2 cm) thick. Cut each disc into 4 equal slices to make 8 scones in all. Transfer to the prepared baking sheet about 1 inch (2.5 cm) apart. Brush the tops with cream.
Bake in the preheated oven until golden, about 12-14 minutes. Let cool for 5 minutes before removing to wire rack.