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 free of lumps.
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 the beaters are lifted.
04 - Gently fold the vanilla extract into the egg mixture. Gradually add the sifted dry ingredients, alternating with the milk, folding carefully 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 gently when pressed with a fingertip.
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 towel. Peel off the parchment paper carefully.
07 - Starting at the short end, tightly roll the cake and towel together into a log. Transfer to a wire rack and cool completely for about 45 minutes.
08 - Gently unroll the cooled cake. Spread the creamy caramel sauce evenly over the entire surface. Sprinkle the toasted chopped pecans in an even layer on top of the caramel.
09 - Carefully re-roll the cake, this time without the towel, keeping it as tight as possible. Place 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 chopped semi-sweet chocolate in a heatproof bowl. Let sit for 2 minutes, then whisk until completely smooth and glossy. Allow to cool slightly until it reaches a pourable consistency.
11 - Pour the ganache over the rolled cake, spreading it evenly across the top and allowing it to drip down the sides. Garnish with additional chopped pecans, a drizzle of caramel sauce, and chocolate shavings as desired.
12 - Refrigerate the cake roll for at least 30 minutes to allow the ganache to set and the filling to firm up for cleaner slices. Wipe the knife clean between each cut. Serve at room temperature for the best texture and flavor.