01 - Preheat oven to 350°F. Line a 15×10-inch jelly roll pan with parchment paper and lightly grease the surface.
02 - In a medium bowl, sift together the all-purpose flour, unsweetened cocoa powder, baking powder, and salt until uniformly blended.
03 - In a large mixing bowl, beat the room-temperature eggs and granulated sugar with an electric mixer on high speed for 5 minutes until the mixture is thick, pale, and forms ribbons when lifted.
04 - Gently fold in the vanilla extract. Gradually add the sifted dry ingredients in alternating additions with the milk, folding carefully after each addition until just combined. Avoid overmixing.
05 - Spread the batter evenly across the prepared jelly roll pan. Bake for 10 to 12 minutes, or until the center springs back lightly when touched.
06 - While the cake bakes, lay a clean kitchen towel flat on the counter and dust generously with powdered sugar. Immediately upon removing the cake from the oven, invert it onto the towel. Peel away the parchment paper. Starting from a short end, roll the cake and towel together tightly. Transfer to a wire rack to cool completely, about 45 minutes.
07 - Gently unroll the cooled sponge. Spread the creamy caramel sauce evenly over the entire surface. Scatter the toasted chopped pecans uniformly across the caramel layer.
08 - Carefully roll the cake back up, this time without the towel, keeping it snug but gentle to avoid cracking. Place seam-side down on a serving platter.
09 - In a small saucepan, heat the heavy cream and unsalted butter over medium heat until just simmering. Pour the hot mixture over the chopped semi-sweet chocolate in a heatproof bowl. Let stand for 2 minutes, then whisk until completely smooth and glossy. Allow to cool slightly until it thickens to a pourable consistency.
10 - Pour the warm ganache over the rolled cake, spreading evenly to coat the top and sides. Garnish with additional chopped pecans, a drizzle of extra caramel, and chocolate shavings as desired.
11 - Refrigerate for at least 30 minutes to set the ganache before slicing. Wipe the knife clean between cuts for neat portions. Allow slices to sit at room temperature briefly before serving for the best texture.