Sift the flour through a fine-mesh strainer into a large bowl. Add the sugar, baking soda and salt. Stir well to combine. Set aside.

In a medium saucepan over medium heat, combine the butter, milk, and cocoa powder. Bring to a boil, whisking frequently until the butter melts completely and the cocoa is incorporated. Add the hot chocolate/milk mixture to the flour mixture, whisking until combined. Add the eggs and vanilla and whisk until well blended. Pour the batter into the prepared pan.

Bake until a toothpick comes out clean, about 18-20 minutes. Transfer to a wire rack and let the cake cool completely in the pan.

Arrange the toasted pecans evenly over the top of the cake. Spoon the glaze over the top, carefully spreading it in and around the pecans. Let the frosted cake stand at room temperature until the glaze sets, about 3 hours. Cut into squares. Serve, or cover with aluminum foil and store for up to 2 days at room temperature.

Chocolate Glaze:
In a medium saucepan over medium heat, combine the cream and corn syrup. Bring to a simmer then reduce the heat to low. Add the chocolate and whisk until melted and smooth, about 1 minute. Remove from the heat and let the mixture stand until lukewarm, about 10 minutes. The glaze should be thick but pourable. Makes about 1 1/3 cups.