This technique is called "debossing", isn't it amazing?
At our last technique class we created this card using Stampin' Up!'s XL Ornament punch (119847),
Square Lattice embossing folder (119976, one of my favourite stamp sets Lovely As A Tree (115026) and Deck The Halls designer paper (120810). You assemble the card THEN you insert it into the embossing folder and run it through the Big Shot, and it comes out looking like this! Love it!