In a saucepan combine butter, sugar and milk , bring to a simmer and cook until sugar dissolves, about 2 minutes.slowly whisk some hot mixture to whisked egg yolks to temper them, adding enough to make them hot. Then slowly wisk in back into saucepan

Cook over medium heat stirring constantly until thickened, about 15 minutes

Remove from heat and stir in vanilla, coconut and pecans, scrape into a bowl and let cool to room temoerature

Melt chopped chocolate in microwave just until smooth, let cool to room temperature

Combine flour, cocoa powder, salt and baking powder in a bowl, whisk to combine, set aside

In a large bowl beat butter and sugar until light and fluffy

Stir in melted chocolate

Add eggs one at a time, beating after each egg

Stir in the flour mixture until well combined. Chill dough 30 to 60 minutes until its easy to roll into balls

Roll dog into 1 inch balls and place 2 inches apart on prepared baking sheets. Bake about 11 minutes until puffed and just set. Cool on pan on wire rack 5 minutes them transfer to racks to cool completely

Place one cookie flat side up on work surface

Spread some cooled coconut pecan filling on cookie

Add another cookie on top and press lightly to make c sandwich. This makes about 20 sandwich cookies