Grease an 8×8 square baking pan with shortening and line with parchment paper that overhangs all four edges.
For the tahini layer: Break the almond bark into pieces and place in a saucepan. Melt over low heat on the stove top until smooth. Stir in the condensed milk and tahini. Mix until well incorporated. The mixture will thicken so work quickly! Spread the mixture in the bottom of the prepared pan and refrigerate until set, about 1 hour.
For the chocolate layer: Combine the semisweet chips and milk in a saucepan and place over low heat. Stir until melted and thoroughly combined. Pour over the tahini layer and immediately top with toasted sesame seed. Refrigerate until firm, about 1 hour.
Cut into 32 one-inch squares. Allow fudge to come to room temperature before serving. Package pieces in lidded containers for holiday gift giving.
To toast sesame seed: place sesame seed in a nonstick skillet and turn to medium-high heat. Stir constantly until golden brown; transfer to a plate to cool.