Lightly oil an 8-inch square baking pan. Line the pan with parchment paper, leaving a 2-inch overhang on two sides. Lightly oil the parchment.
In a small pot, or in a microwave-safe bowl, heat the cream and butter together until melted. Add 6 ounces of the chocolate and let it stand for 2 minutes. Whisk until smooth and set aside.
In a medium saucepan over medium-high, heat the sugar, corn syrup, and the water until the sugar turns deep amber, swirling the pan to caramelize the sugar evenly, 10 to 12 minutes. Remove from the heat and add the chocolate mixture. Be careful: This will bubble up and sputter. Stir until smooth. Add the salt.
Attach a candy thermometer to the side of the pot and return the pan to the heat. Cook the mixture over medium heat until the candy thermometer reads between 248° F and 250° F, 8 to 10 minutes, stirring constantly. Pour into the prepared pan but do not scrape out anything that clings to the pan. Let cool at room temperature until firm, at least 2 hours.
Cut around the edges to release the caramel from the pan. Using the parchment, lift the block of caramel out of the baking pan and set on a cutting board. Cut into 1-inch squares with a long, sharp knife. Line a baking sheet with parchment paper.
In a medium heat-proof bowl, melt the remaining 8 ounces chocolate in short bursts in the microwave or over a double boiler. Using two forks, dip each caramel in the melted chocolate and swirl it around to coat. Tap each candy against the edge of the bowl a few times to release excess chocolate. Transfer chocolate-covered caramels to the prepared pan. Sprinkle with flaky sea salt. Chill for 20 minutes to set the chocolate. Store caramels in an airtight container in the fridge.