In a large mixing bowl, whip the butter and sugar together. Then beat in the egg and vanilla. Sift together the flour and baking powder and stir in.
Chill for at least one hour. Then roll out to cut in rounds.
Preheat the oven to 350° F. Bake for 8-10 minutes until only light browned on the edges. Depending on the size of your cookie cutter, this should make about 30 cookies or 15 sandwich cookies.
Sucre à la Crème Filling
Pour the cream into a large pot. Stir in the brown sugar. Put a candy thermometer on the side without the bottom of the thermometer touching the pot.
Begin heating over medium-high heat until the mixture reaches the softball stage. It will rise and heat to 100 F. Then keep at a rolling boil. The mixture will continue to bubble “splashy” bubbles. When the bubbles become less “splashy” and start leaving craters in the surface, start checking to see if it’s at the soft-ball stage.
Fill a clear glass with icy cold water. Drop a small amount of the mixture in. If it makes threads, it’s not cooked long enough. If it makes a small ball shape, see if you can scoop it out of the cup and press it. If it flattens into a pancake it’s done cooking. If it dissolves it’s not ready. Check often, if you cook too long it will go to a hard-ball stage and this is not what you want.
Once cooked to soft-ball stage, remove from heat. Continue to stir. Stir and cool until a spoon lifted and waved around leaves a trail in the mixture. Spoon a small amount to place on one cookie and then top with another. Work quickly as the mixture cools into a solid state when fully cooled.
Any left-over mixture can be pressed into a greased pan and let set and cut into squares.
Go Nuts! (That’s Mona’s recommendation, there)
Recipe by Just a Smidgen at https://justasmidgen.com/2012/05/16/biscuits-sucre-a-la-creme/