CREATE THE ENHANCED ORANGE SHORTBREAD BASE:
Preheat oven to 160°C (325°F). In food processor, pulse flour, sifted powdered sugar, salt, and orange zest until well combined. Add cold butter cubes and pulse until mixture resembles coarse breadcrumbs with some visible butter pieces. Add orange juice and vanilla, pulsing just until dough begins to come together - don't overprocess. Turn onto lightly floured surface and gently press into disc. Roll between parchment papers to exactly 8mm thickness. Cut into 7.5cm rounds and place on parchment-lined baking sheet. Bake for 15-18 minutes until edges are lightly golden but centers remain pale. Cool completely on wire rack.

PREPARE THE SILKY ORANGE CARAMEL:
In heavy-bottomed saucepan, heat sugar over medium heat, stirring constantly until melted and deep amber (160°C/320°F). Remove from heat immediately and carefully whisk in warm cream - mixture will bubble vigorously. Whisk in butter pieces, orange zest, orange juice, and salt until completely smooth. Return to low heat and cook for 2-3 minutes until mixture coats spoon heavily. Transfer to shallow dish and cool until spreadable but not set - it should hold its shape but flow slowly.

MAKE THE CHOCOLATE ORANGE GANACHE:
Place chopped chocolate in heatproof bowl. Heat cream in saucepan until just beginning to simmer. Pour hot cream over chocolate and let sit for 2 minutes. Whisk from center outward until smooth and glossy. Add orange liqueur and softened butter, whisking until fully incorporated. Cool until just spreadable but not thick.

EXECUTE PROFESSIONAL ASSEMBLY WITH ACETATE COLLARS:
Cut acetate sheets into strips 5cm high and long enough to wrap around each shortbread round. Create collars by wrapping acetate around each shortbread base, securing with tape. Place shortbread rounds in bottom of collars. Spread exactly 8mm layer of orange caramel over each shortbread, using offset spatula for even distribution. Refrigerate for 30 minutes until caramel is firm. Add thin layer of chocolate ganache over set caramel, spreading carefully to avoid disturbing lower layer. Chill for another 30 minutes.

TEMPER THE CHOCOLATE FOR PROFESSIONAL FINISH:
Melt 150g chocolate in double boiler to 50°C (122°F), stirring constantly. Remove from heat and add remaining 75g chocolate, stirring until temperature drops to 29°C (84°F). Briefly reheat to 31°C (88°F) for proper temper. Pour tempered chocolate over ganache layer, spreading evenly to collar edges. Refrigerate for 2 hours until completely set.

FINAL PRESENTATION:
Carefully remove acetate collars by warming slightly with hair dryer if needed. Trim any uneven edges with warm, dry knife. Bring to room temperature for 15 minutes before serving for optimal texture contrast. Cut with sharp knife, cleaning blade between cuts for neat presentation.