• Place the can of evaporated milk in the fridge to chill for at least two hours or overnight. Keep it there right up until you're ready to start whipping it.
• Place a large metal or glass bowl, or the bowl of a stand mixer in the fridge or freezer to chill.

Graham Cracker Crust

• Move an oven rack to the middle position and heat the oven to 350°F.
• Pulse the 12 whole graham crackers together in a food processor until they form fine crumbs. Alternatively, place the crackers in a 1-gallon freezer bag and roll over them with a rolling pin. Measure out 1/4 cup of the crumbs and set aside in a small bowl.
• Transfer the remaining crumbs to a medium bowl. Stir in the 1/4 cup unsalted butter, 1 Tablespoon granulated sugar, and 1 pinch salt until the mixture resembles wet sand. Press the graham crumb mixture firmly into the bottom of a 9x13" baking pan. Bake until fragrant, about 10 minutes. Turn off the oven, and cool the crust completely.

Lemon Cloud

• Using a microplane or lemon zester, zest one of the lemons (you should have about 1 teaspoon of zest). Juice the lemons and measure out 1/2 cup of lemon juice. Mix the lemon juice and zest together in a small bowl or measuring cup. Set aside.
• Pour 1/2 cup of cold water into a medium bowl. Sprinkle the 2 Tablespoons unflavored gelatin powder over the top of the water and allow it to hydrate for about 5 minutes.
• Heat the remaining 1/2 cup of water in the microwave on high heat until hot and steaming, about 1 minute. Pour the hot water over the gelatin, and stir until dissolved. Stir the 3/4 cup granulated sugar into the gelatin mixture until dissolved. Stir in the lemon juice mixture.
• Place the bowl of the lemon gelatin mixture in the fridge until it starts to cool, and just starts to thicken, about 20-30 minutes. Make sure to check on it, and stir it often to ensure that it doesn't fully set.
• Meanwhile, pour the chilled evaporated milk into the chilled bowl. Mix on high speed until soft peaks form, about 3-4 minutes. Fold the semi-set gelatin mixture into the whipped evaporated milk. Mix on medium-high speed until fully mixed and stiff peaks form, about 1-2 minutes.
  
• Gently spread the whipped lemon mixture over the graham cracker crust in the baking pan. Sprinkle with the remaining graham crumbs, then cover carefully with plastic. Place in the fridge to chill for at least 1 hour before serving. Cut into pieces, and serve.