Pre heat oven to 350 Fahrenheit
Mix the flour, corn starch and sugar
add the diced butter and mix well until you form the dough
At first the mix will be dry and crumbly but keep working the dough until it's soft and uniform
Roll the dough about 1 inch thick
cut the cookies with a biscuit cutter
bake at 350 for 10 minutes
remove cookies from the oven and let them cool down completely before adding the dulce de leche
Once cooled down, add a layer of dulce de leche. I like to use a pipping bag for this to avoid pressing too hard on the cookie.
add the other cookie to form the sandwich and sprinkle with confectioner's sugar