Make raspberry sauce: Combine raspberries, 1 tablespoon sugar, and 1 teaspoon vanilla in small saucepan over medium heat. Simmer 5-8 minutes until thickened. Strain through fine-mesh strainer to remove seeds. Set aside to cool.

Prepare cheesecake topping: Beat room-temperature cream cheese with ⅓ cup sugar using electric mixer until smooth, about 1 minute. Add 1 egg and ½ teaspoon vanilla, beating on low just until combined. Set aside.

Preheat and prep: Preheat oven to 350°F (175°C). Line 8×8-inch square pan with parchment paper, leaving overhang on two sides for easy removal.

Mix brownie dry ingredients: In medium bowl, whisk together flour, sifted cocoa powder, and salt. Set aside.

Mix brownie wet ingredients: In large bowl, whisk oil, 1½ cups sugar, and 1 tablespoon vanilla until combined. Add 3 eggs one at a time, whisking vigorously after each until mixture becomes glossy.

Combine brownie batter: Fold dry ingredients into wet ingredients just until no streaks remain. Don't overmix. Batter will be thick and glossy.

Assemble layers: Pour brownie batter into prepared pan and spread evenly. Pour cheesecake mixture over brownie layer and spread gently to edges. Drop spoonfuls of cooled raspberry sauce randomly across surface.

Create swirl: Use butter knife or skewer to swirl raspberry sauce through cheesecake in figure-eight pattern. Don't overswirl or colors will muddy.

Bake: Bake 30-35 minutes until edges are set and center jiggles slightly when gently shaken. Don't overbake. Cool on wire rack 30 minutes.

Chill and cut: Refrigerate at least 2 hours or overnight. Lift from pan using parchment overhang. Use heart-shaped cookie cutter to cut shapes, wiping cutter clean between cuts.