Add the unsalted butter, granulated sugar, fine sea salt, and vanilla bean paste to a stand mixer bowl. Using the paddle attachment, beat on medium speed for 3 minutes or until light and fluffy.
Add the egg yolk to the stand mixer bowl and beat on low speed for about 30 seconds, or until fully incorporated.
Add the all-purpose flour and beat on low speed, just until the dough begins to come together. Shape into a rectangle, wrap in plastic wrap and refrigerate for 30 minutes.
Lightly dust a large flat surface with flour.
Unwrap and roll out cookie dough, while chilled, to about 1/8-inch thickness. Cut dough into desired shapes using biscuit cutters or cookie cutters. Arrange cookies on parchment lined cookie sheets, about 1 inch apart.
Bake in preheated oven for 16 minutes, or until cookies are lightly golden around the edges.
Remove cookie sheets from oven and cool on wire racks.
Store leftover cookies in an airtight container for up to 3 days.
Notes
*Chill cookies on trays before baking for 30 to 60 minutes for cookies with a little less rise in them.