Step 1

Blend rice, cinnamon, and ¾ tsp. salt in a blender to a fine powder. Stir rice mixture and cream in a large bowl until no lumps remain; cover and chill at least 3 hours and up to 6 hours. Strain through a fine-mesh sieve into a large bowl, pressing on solids; reserve rice for another use.

Step 2

Using an electric mixer on high speed, beat cream in a large bowl to stiff peaks, about 3 minutes; set aside.

Step 3

Whisk egg whites, granulated sugar, and a pinch of salt in a medium heatproof bowl set over a saucepan of simmering water (do not let bowl touch water). Cook, whisking constantly, until sugar is dissolved and an instant-read thermometer inserted into the mixture registers 130°, about 4 minutes. Remove bowl from heat and, using an electric mixer on high speed, beat until mixture is tripled in volume, glossy, and cool, 10–12 minutes (this will take only about 6 minutes if using a stand mixer fitted with whisk attachment).

Step 4

Gently fold reserved cream into meringue until mixture is smooth. Scrape into an 8x8" baking pan; cover and freeze until set, at least 3 hours.

Step 5

Meanwhile, lightly coat a large heatproof bowl with nonstick spray. Place kamut in bowl. Bring brown sugar, butter, tequila, and corn syrup to a boil in a medium saucepan, stirring to dissolve sugar. Cook, stirring often, until caramel is a deep amber, 10–12 minutes. Quickly pour caramel over kamut and mix with a heatproof spatula to coat. Transfer to a parchment-lined rimmed baking sheet and let cool. Break into small pieces.

Step 6

Scoop semifreddo into bowls and top with caramel kamut.

Step 7

Do Ahead: Semifreddo can be made 3 days ahead; keep frozen. Let sit at room temperature 30 minutes before scooping. Caramel kamut can be made 1 day ahead; store airtight between layers of paper towels at room temperature.