Step 1: Prep the Pans
Let’s dive in with joy!—line four 8-inch round pans with plastic wrap and pop them in the freezer to chill (I’m buzzing with excitement!). Cold and ready—pans are set (my kitchen’s alive!). It’s the frosty start—pure foundation!

Step 2: Make the Cookie Base
Mix ½ cup chocolate cookie crumbs with 2 tablespoons melted unsalted butter—stir until it’s like wet sand (my kitchen’s humming!). Press into one chilled pan—freeze for 15 minutes (my enthusiasm’s soaring!). Crunchy and firm—base is done (my heart’s full!). It’s the toasty bedrock—pure texture magic!

Step 3: Layer the Vanilla
Pull out the base pan—spread 1 quart vanilla ice cream over the crust, smoothing the top (my kitchen smells like sweetness!). Cover with plastic—freeze for 4 hours (my anticipation’s climbing!). Creamy and solid—layer one’s set (my heart’s happy!). It’s the soft beginning—pure comfort born!

Step 4: Add Chocolate and Birthday Cake Layers
Work fast with the other chilled pans—press 1 quart chocolate ice cream into one and 1 quart birthday cake ice cream into another, smoothing both (my kitchen’s a rainbow!). Cover with plastic—freeze 4 hours (my counter’s a festival!). Bold and firm—layers ready (my heart’s leaping!). It’s the vibrant core—pure party forming!

Step 5: Stack the Cake
Unmold the frozen layers—stack starting with the cookie-vanilla base (my kitchen’s buzzing!). Add the chocolate layer—press firmly (my excitement’s rising!). Place the 8-inch brownie round—push to stick (my nose is in love!). Top with the birthday cake layer—wrap tightly and freeze (my heart’s racing!). Tower built—cake united (my freezer’s a vault!). It’s the grand assembly—pure joy solidified!

Step 6: Craft the Ice Cream Crown
Line an 8-inch springform pan with plastic—keep it on ice (my kitchen’s a workshop!). Open 4 pints Häagen-Dazs ice cream—store them on ice (my counter’s sparkling!). Scoop small balls and press into the pan, weaving in 12 mini meringues—build a mounded peak (my heart’s pounding!). Freeze 4 hours until rock-solid (my freezer’s humming!). Frosty and festive—crown’s ready (my excitement’s bursting!). It’s the dazzling topper—pure celebration peak!

Step 7: Whip the Frosting
Soak 1 sheet gelatin in warm water—or mix 1 teaspoon powdered gelatin with 1 tablespoon water until smooth (my kitchen’s precise!). Beat 1 cup whole cream with 2 tablespoons cane sugar in a chilled mixer bowl—medium speed for 30 seconds (my whisk’s dancing!). Drizzle in the gelatin mix—crank to high and whip to stiff peaks, not grainy (my heart’s singing!). Chill up to 1 hour (my counter’s waiting!). Fluffy and firm—frosting’s perfect (my kitchen’s calm!). It’s the silky cloak—pure cloud ready!

Step 8: Assemble the Cake
Spread a dab of whipped frosting on a cake stand—unmold the ice cream tower and center it (my kitchen’s a stage!). Frost the top and sides thickly with whipped cream (my hands are flying!). Unmold the ice cream crown—set it atop like a tiara (my table’s gasping!). Freeze a few more hours (my heart’s soaring!). Stunning and solid—cake’s complete (my freezer’s a shrine!). It’s the big reveal—pure frozen glory!

Step 9: Decorate and Serve
Scoop leftover whipped cream into a piping bag with a star tip—pipe swirls around the base (my kitchen’s glowing!). Sprinkle 2 tablespoons mini chocolate chips on top (my counter’s a party!). Keep frozen until serving—slice and share (my heart’s thrilled!). Creamy and festive—ready to wow (my table’s alive!). It’s the final flourish—total birthday bliss!