Preheat oven to 350°F. Grease and line an 8 inch cake pan with parchment paper.

In a food processor, pulse pistachios into very fine crumbs.

Then transfer into a large bowl and add flour, salt, baking soda and baking powder, and whisk to combine well. Set aside.

In the bowl of a stand mixer fitted with a paddle attachment, beat butter on medium speed until lightened in color and fluffy, 2 to 4 minutes. Add sugar and beat until well combined, 2 to 4 minutes. Add egg and egg white, and beat on medium high speed for 2 minutes. Add sour cream, milk, and extracts, and beat on medium speed until just combined.

Remove bowl from mixer and add dry ingredients. Use a large rubber spatula to fold them in until just combined.

Gently pour batter into prepared pan and bake for 25 to 30 minutes, or until a toothpick inserted into the center comes out clean.

Remove cake from oven and cool on a wire rack for 20 minutes, then turn out onto wire rack to cool completely.

While the cake cools, move ice creams to the refrigerator to begin softening.

Once cake is cool, line a 9 inch mixing bowl with several layers of plastic wrap, leaving 10+ inches of overhang to cover the bowl later. Place 1 ½ cups of chocolate ice cream in the bowl and use a spoon or rubber spatula to smooth into an even layer. Place the bowl in the fridge for 10 minutes uncovered to firm up slightly. Next, add the full pint of vanilla ice cream and spread into an even layer. (If vanilla ice cream isn’t soft enough to spread easily, leave the pint at room temperature for about 10 minutes.) Place bowl back in freezer for 10 minutes to firm, then repeat the process with strawberry ice cream. Place back in freezer for 30 minutes uncovered to firm up, then cover and freeze for at least 4 hours, and up to 2 days.

When ready to assemble, remove ice cream bowl from freezer, unwrap plastic wrap covering, and invert cooled pistachio cake on top of ice cream bowl. Place a large plate or tray beneath the cake, then invert the ice cream bowl and cake together, so that the dome of ice cream sits on top of the cake. The plastic wrap should help the bowl lift off cleanly, but if it sticks, sit it in a larger bowl of hot water for 20-30 seconds and try again.

Once cake and ice cream layers are inverted, remove the bowl and plastic wrap, then place tray in freezer while you make the meringue.

In the bowl of a stand mixer fitted with the whisk attachment, add egg whites and beat on medium speed until whites begin to turn foamy, 30-60 seconds. Add 2 tablespoons of sugar, cream of tartar, and vanilla extract, and continue beating until silky, soft peaks begin to form, 2-3 minutes. Reduce to medium-low speed and slowly add the remaining sugar, 2 tablespoons at a time, until the sugar is completely incorporated and the meringue holds glossy, stiff peaks, 8-10 minutes total.

Scoop meringue into a large piping bag fitted with a star tip.

Remove Baked Alaska from the freezer, and pipe approximately 1 inch stars all over the dome of ice cream, ensuring there are no gaps in the meringue coating. Nestle the egg shell into the top of the meringue, then place in freezer until ready to serve, up to 4 hours.

Once ready to serve, remove Baked Alaska from freezer, and use a torch to toast the meringue until it is golden brown all over.

To flambé the meringue, warm the rum in a small pot over very low heat (do not let it simmer or boil). Ladle warm rum into the egg shell until it is full, and then carefully ladle or pour the remaining rum into the shell so that it overflows down the cake, lighting the stream from your ladle with a long reach lighter while it’s flowing.

Once the alcohol burns off, run a chef’s knife under hot water for 20-30 seconds, then slice and serve immediately.