• Set out two baking sheets and line one with parchment paper, have parchment paper ready for the other.  Cut a few long pieces of wax paper for rolling out the cookies. 
• Get a medium sized bowl and weigh the flour into it then whisk in the salt and ube powder and set aside
• Using a large mixing bowl and a hand mixer or a stand mixer, cream the butter and sugar together until light and fluffy, scraping down the sides when needed. Add in the egg yolks one at time, mixing well between additions, again scraping down the sides of the bowl when needed.
• Add in the ube extract and mix well then add in the flour mixture and mix until the dough is evenly mixed and colored. 
• Divide the dough into to pieces then shape into disks and wrap well with plastic wrap then place in a resealable bag. Chill for at least 4 hours. 
• Preheat oven to 350 Deg F ( 160C) and set out a couple baking sheets and line with parchment paper. 
• Working with one disc at a time carefully roll out between two sheets of wax paper, do not flour the wax paper or the dough. You want the dough rolled out to between ⅛th and ¼th of an inch (3-6 mm).
• Transfer the rolled out dough still on the wax paper to a baking sheet and chill for about 5 minutes until firm. 
• If using an embossing roller, dust the roller with flour using a pastry brush. Transfer the rolled out dough from the baking tray to a flat surface ( kitchen counter). Take the embossing rolling pin and press down into the dough and roll away from you. Do not roll back if you missed any of the dough. You want to press down firm enough to emboss the dough but not so firm that it sticks to the roller. If it does stick, gently remove the stuck dough with a toothpick, reddest the roller and start rolling again from where you stopped, not from the beginning again. This might take a time or two to get the hang of it. 
• Carefully transfer the embossed dough back to the baking sheet and chill again until firm. Each chilling step just takes a few minutes. 
• Once again transfer the chilled, embossed dough to the kitchen counter and cut out your cookies with a 2 inch circular cutter, dipping the cutter in flour between each cookie so the dough doesn’t stick to it. Using a thin spatula carefully transfer the cut out cookies to a baking sheet lined with parchment paper. 
• And back to chilling again before baking since the dough thaws pretty quickly due to being rolled out somewhat thin. Just a few more minutes until firm.
• Bake the chilled cookies for 8-9 minutes until looking dry and set, you don’t want them to brown. 
• Cool on the baking sheet for 5 minutes then carefully transfer to a wire cooling rack to cool completely. Since these are more on the fragile side for cookies, I suggest to freeze them before filling.

For the frosting:

• Combine all the ingredients in a large bowl and mix until smooth using a hand mixer or this can be done in a stand mixer.
• Transfer to a pastry bag and cut off the tip so you have a big enough opening to pipe a circle around the edges. 
• Spread a teeny bit of the frosting on the bottom of one cookie, then pipe frosting around the edge to make a little well for the jam. Spoon in about a half a teaspoon or so of jam then top with another cookie. Repeat until all cookies are filled. 
• Keep cookies in an airtight container in the freezer. These soften up with the filling and will be very soft and crumbly at room temperature.