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 well combined and aerated.
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 becomes thick, pale, and doubles in volume.
04 - Mix the vanilla extract into the whipped egg mixture. Gradually fold in the sifted dry ingredients, alternating with the milk, using a gentle folding motion until just combined. Do not overmix.
05 - Spread the batter evenly across the prepared jelly roll pan. Bake for 10 to 12 minutes, or until the top springs back lightly when touched and a toothpick inserted in the center comes out clean.
06 - While the cake bakes, lay a clean kitchen towel flat on the counter and dust it generously with powdered sugar. Immediately upon removing the cake from the oven, invert it onto the prepared towel. Carefully peel off the parchment paper.
07 - Starting from one short end, tightly roll the cake and towel together into a log shape. Place seam-side down on a wire rack and allow to cool completely, approximately 45 minutes.
08 - Gently unroll the cooled cake. Spread the creamy caramel sauce evenly across the entire surface. Sprinkle the toasted chopped pecans uniformly over the caramel layer.
09 - Carefully re-roll the cake (without the towel this time), keeping it as tight as possible. Place the roll seam-side down on a serving platter.
10 - In a small saucepan, heat the heavy cream and unsalted butter over medium heat until just simmering. Pour the hot mixture over the finely chopped semi-sweet chocolate in a heatproof bowl. Let it sit for 2 minutes, then whisk vigorously until smooth and glossy. Allow to cool slightly until it reaches a pourable consistency.
11 - Pour the warm ganache over the rolled cake, spreading evenly across the top and allowing it to drip down the sides. Garnish with additional chopped pecans, caramel drizzle, and chocolate shavings as desired.
12 - Refrigerate the assembled cake roll for at least 30 minutes before slicing to allow the ganache to set and the filling to firm up for clean portions. Allow to come to room temperature before serving for the best texture.