Instructions

• Pour 1 1/2 cups of water into the Instant Pot insert and place the trivet inside.
• Line a 7-inch springform pan with a parchment paper round. Grease the sides and the parchment-lined bottom lightly with some of the unsalted butter.
• In a medium microwave-safe bowl, combine 15 tablespoons unsalted butter, 1 1/2 cups semisweet or bittersweet chocolate chips, and 4 tablespoons unsweetened Dutch-processed cocoa powder.
• Microwave the chocolate–butter mixture on high in 30-second intervals, whisking well after each interval, until fully melted and smooth.
• Add 1/2 teaspoon fine sea salt, 1/2 cup white granulated sugar, and 1 cup light brown sugar to the warm chocolate mixture and whisk until combined.
• Stir in 2 tablespoons strong coffee-like liquid espresso and 2 teaspoons pure vanilla extract.
• Add the 6 large room-temperature eggs to the chocolate mixture one at a time, whisking after each addition until the batter is smooth and homogeneous.
• Pour the batter into the prepared springform pan and gently tap the pan on the counter a few times to release any large air bubbles.
• Cover the pan tightly with aluminum foil. Place the covered pan on the trivet in the Instant Pot.
• Close and lock the lid, set the pressure release valve to SEALING, select Manual (High Pressure), and set the cooking time to 50 minutes.
• When the cooking time ends, let the pressure release naturally for 10 minutes, then carefully move the valve to VENTING to release any remaining pressure. When the float valve drops, open the lid.
• Using oven mitts or a dish towel, carefully remove the covered pan from the pot. Remove the foil and check the center: if it jiggles just slightly, it is done; if the center is liquidy, re-cover the pan with foil, return it to the trivet in the Instant Pot, reseal, and cook an additional 5 to 10 minutes on high pressure, then perform a 10-minute natural release before quick-releasing any remaining pressure and checking again.
• Let the cake cool to room temperature on the counter (about 2 hours). Run a thin long knife around the edge of the cake and release the springform sides.
• Refrigerate the cake if desired or serve warm. Just before serving, dust the top with additional Dutch-processed cocoa powder.