In a medium bowl, whisk together flour, baking powder, and sea salt.

In a separate bowl or the bowl of a stand mixer, mix butter on high speed until soft and fluffy.

Mix in the granulated sugar, followed by the egg and vanilla bean paste.

Add the dry ingredients and mix on low speed until just combined. Use your hands to finish bringing the dough together.

Flatten dough  into a disc. Wrap in plastic wrap and chill in the refrigerator until firm, at least 2 hours or overnight.

Line a large baking tray, or several smaller trays, with parchment or silicone mats. (I opted for small trays, because they fit nicely in my fridge.)

On a floured countertop or a silicone rolling mat, use a floured rolling pin to roll the chilled dough to 1/4-inch thickness.

With a 1 3/4-inch round cutter, cut the dough into circles. Transfer to prepared tray.

Re-roll the scraps. Use a sharp chef’s knife to cut rectangles, approximately 1 x 2 inches.

Transfer tray to the refrigerator to chill for 30 minutes. Meanwhile, preheat oven to 350° F / 176° C.

Bake chilled cookies for 11-12 minutes, or until cookies are very lightly golden brown around the edges.

Transfer cookies to a wire rack to cool. Meanwhile, prepare the buttercream.

Buttercream:

In a large mixing bowl or the bowl of a stand mixer, whip butter until light and fluffy. Gradually add the confectioner’s sugar, alternating with the milk and mixing well after each addition.

Add the vanilla bean paste and sea salt and mix on hight speed for 3-5 minutes. If necessary, add more confectioner’s sugar or milk to adjust the consistency. The buttercream should be thick and creamy—soft enough to pipe, but firm enough to hold its shape.

Transfer half of the buttercream to a piping bag fitted with a 1/8 – 1/4-inch round tip.

Assembly:

Round “sushi roll” cookies:

With a small stepped palette knife, apply a layer of buttercream to the top of the cookie.

Wrap a licorice whip around outside the edge.

Add gummy candies as desired. You can make cookies resembling tuna rolls, California rolls, salmon rolls, avocado rolls, oshinko rolls, and more.

Pipe dots of buttercream “rice,” covering the entire surface of the cookie.

Sprinkle with sesame seeds, if desired.

Rectangular “nigiri” cookies:

With a small stepped palette knife, apply a layer of buttercream to the top of the cookie.

In a strawberry belt or gummy pencil, trimming the candy to fit the length of the cookie.

Pipe dots of “rice” along the sides of the candy.

Add a piece of black licorice in the middle, trimming the edges to fit the width of the cookie.

Allow cookies to sit at room temperature until the buttercream sets. Store cookies in a single layer in an airtight container at room temperature for up to three days.