Before churning or pacotizing the chocolate ice cream base, line 1 half sheet pan with a nonstick rubber mat and a 25cm / 10in by 38cm / 15in by 2-cm / .75-in stainless steel or Plexiglas frame. Line another half sheet pan with a nonstick rubber mat. Place both sheet pans in the freezer.
Line a cutting board with an acetate sheet and freeze.
Churn or pacotize the chocolate ice cream and pour it into the frozen pan with the frame. A 2-cm / .75-in-deep frame will hold a little over 1.75 L / 1.8 qt of liquid, but don’t forget to take overrun into account. In this case, there should be an overrun of 50 percent. Using an offset spatula, spread the ice cream evenly so that it fits exactly into the frame, and remove any excess. Work fast to avoid any melting. Place the ice cream back in the freezer.
Once the ice cream has hardened, remove the Plexiglas frame by cutting around the inside border with a paring knife (be careful not to cut through the nonstick rubber mat). Flip the ice cream onto the acetate-lined cutting board and peel off the nonstick rubber mat. Cut two 12.5-cm / 5-in squares and transfer them to the other frozen sheet pan lined with the nonstick rubber mat. Freeze to harden, then cover with plastic wrap.
Place 2 square stainless steel molds 15cm / 6in by 5cm / 2in deep in the freezer on a sheet pan lined with a nonstick rubber mat.
Churn or pacotize the Grand Marnier ice cream and transfer it to a piping bag; reserve frozen until needed.
The entremets will be assembled upside down. Pipe the Grand Marnier ice cream into the frames set in the freezer. Make sure to get into the corners to avoid air pockets. Fill up to 1.75cm / .68 in high, using half of the mixture for both frames. Use an offset spatula to even it out. Tap the sheet pan down gently to get any air pockets out. It’s okay if some of the ice cream comes out the sides; it is a sign that there will be little, if any, air pockets.
Quickly place the chocolate ice cream squares on top of the Grand Marnier ice cream, making sure they are centered.
Pipe more Grand Marnier ice cream around the chocolate ice cream first, making sure to pipe into the corners and into the first layer of Grand Marnier ice cream (also, to prevent air pockets). Fill to just under .4 cm / ⅛ in from the top.
Place the crème fraîche cake at the center of the entremets and push down gently until the cake is flush with the rim of the frame.
Put a sheet of parchment paper on the cakes, and 4 sheet pans on top of the cakes to weigh them down and even them out. Freeze until hardened.
Place a square cake board on each of the cakes. It should be slightly smaller than the actual entremets. Make sure the cake board is thin, so it doesn’t lift the cake up too high, which makes it look awkward.
Once hardened, flip the sheet pan over onto another sheet pan. Gently torch the cake molds and lift them up. Return the entremets to the freezer.
Set up the couverture and chocolate spraying area.
Place a sheet pan lined with parchment paper and fitted with a wire rack in the freezer.
Pour the tempered chocolate into a piping bag. Drizzle it on one side of the entremets.
Spray the entire cakes with the white couverture spray.
Spray dark chocolate spray on the opposite side where the chocolate was drizzled.
Place the candied orange zest in a thin straight line on the opposite side of the drizzled chocolate, from one side to the other of the cake.