To make the ice cream dome, remove the ice cream from the freezer and allow to soften slightly. Line a 3-quart bowl with plastic wrap. In another bowl, beat the marmalade into the softened vanilla ice cream with a wooden spoon until combined.
Spoon 2 cups of the orange-vanilla ice cream into the bowl and smooth with a spoon or offset spatula to even. Top with the chocolate ice cream, again smoothing to even, tand hen top the chocolate layer with the remaining 6 cups orange-vanilla ice cream. Cover the surface with plastic wrap and freeze until the ice cream is very hard, at least 4 hours or up to 24 hours.
Turn the brownie out onto a large, flat, ovenproof plate. Unmold the ice cream dome on top of the brownie layer. Place the cake back in the freezer. Hold in the freezer until the meringue is ready.
In electric mixer fitted with the whisk attachment, whip the egg whites and cream of tartar for 2 minutes on medium-high speed until fluffy. Increase the speed to high and add the sugar in a slow stream until stiff, glossy peaks form, 8 to 10 minutes.
Remove the ice cream dome from the freezer. Remove the plastic wrap. Cover the ice cream dome completely with the meringue, using the back of a spoon to make swirly peaks. (Alternately, place the meringue in a pastry bag fitted with a rose tip and pipe spikes for a hedgehog look.) Freeze for at least 3 hours or up to 2 days.
When ready to serve, preheat the oven to 500 degrees F. Bake until the peaks start to turn a golden brown color, 3 to 5 minutes. For easier slicing, let the cake stand for 30 minutes. Slice and serve.
Preheat your oven to 325 degrees F. Spray a 9-inch round cake pan with cooking spray, line the bottom of the pan with parchment paper and grease the parchment well.
For your brownie batter, melt your butter in a medium (or large) heatproof bowl over a pot of simmering water.
While the butter is melting, whisk the cocoa powder, sea salt and sugar in a separate bowl. (The sugar and salt will work as abrasive agents to get any lumps out of the cocoa.) Whisk the cocoa/sugar/salt combo into the melted butter until the sugar has dissolved fully. The mixture should look like fudge and pull away from the bowl into a ball. Take off the stove and set the pan on a dishtowel on your counter. Allow the fudgy mixture to cool down until it's warm, but not hot anymore.
Stir the vanilla into the cooled fudge mixture to loosen it up. Add the eggs into the mixture 1 at a time, adding the second egg after the first egg is fully incorporated. The batter should look shiny and well blended. Add in your flour and stir it until it's fully incorporated. Once it looks fully blended, beat the batter vigorously for at least 45 strokes. This'll not only get out any pent up stress, but it will make the brownies chewy. Fold in your chocolate chips. Spread the thick and fudgy brownie batter evenly in the lined pan with an offset spatula or your greased hands.
Pop the brownie in the oven and bake until they get a nice crust and your house smells like brownies, 20 to 25 minutes. Let them cool completely on a rack or a dishtowel on your counter.