Step 1

In a small saucepan over medium-low heat, bring dates and bourbon to a simmer; cook, stirring, until almost all of liquid is absorbed. Remove from heat; cover and let cool. Purée in a food processor until smooth. (You should have about 1 cup.)

Step 2

Preheat oven to 325°F. Butter a 9-inch springform pan. Line bottom with parchment; butter parchment. Dust pan with cocoa, tapping out any excess.

Step 3

In a heatproof bowl set over (not in) a pan of simmering water, melt butter and chocolate, whisking until smooth. Remove from heat. Whisk in 2/3 cup date purée. Let cool; whisk in egg yolks, kosher salt, and cinnamon.

Step 4

Beat egg whites on medium-high speed until soft peaks form, about 2 minutes. Slowly add 1/4 cup sugar, beating until stiff glossy peaks form. Fold one-third of whites into chocolate mixture, then fold in remaining whites. Transfer to prepared pan, smoothing top with an offset spatula.

Step 5

Bake until set, cracking a bit on edges, and shiny in center, about 30 minutes. Transfer pan to a wire rack and let cool completely. Run a paring knife around sides of pan; remove from pan and transfer to a cake plate.

Step 6

In a small saucepan over medium-high heat, bring remaining 1 cup sugar and 1/4 cup water to a boil, stirring until sugar is dissolved. Let boil, without stirring, until deep golden brown, swirling pan to color evenly, and washing down sides of pan with a wet pastry brush to keep crystals from forming, 10 to 11 minutes. Remove from heat; carefully pour in cream (it will spatter), stirring to combine. Stir in remaining 1/3 cup date purée. Pass caramel through a fine sieve to remove lumps. Let cool until thick but pourable, about 30 minutes.

Step 7

Pour caramel over cake, spreading with an offset spatula so it drips over sides. Sprinkle with flaky salt. Slice cake with a knife dipped in hot water, then wiped down between slices; serve with whipped cream.