This recipe is adapted from Sara Foster's New York Style Crumb Cake. I've added toasted pecans and extra salt (in both the cake batter and cinnamon streusel). The salt mediates the sweet flavor and adds depth to this cinnamon streusel coffee cake.
Preheat the oven to 350° F and spread 1 cup pecans into a single layer on a baking sheet. Bake for 8-10 minutes until the pecans are toasted and fragrant. Remove from the oven and roughly chop.
PREPARE THE BAKING PAN:
Reduce the oven temperature to 325° F.
Spray an 11x7" baking pan with vegetable spray and line the bottom and sides with parchment paper. (Cut the paper 7" wide and about 16" long so that the bottom is covered and there is an overhang on either side of the pan.)
FOR THE CINNAMON STREUSEL TOPPING:
In a large bowl, combine 2½ cups all purpose flour, 1 cup light brown sugar, 2¼ teaspoons cinnamon, ½ teaspoon iodized salt and whisk to blend. Make a well in the center of the flour mixture and add 2 sticks unsalted melted butter to it. Mix to combine.
Add the chopped toasted pecans to the crumble mixture and toss with your clean hands until well combined. The topping should have a loose, crumbly consistency. Set aside.
FOR THE CAKE LAYER:
Add1½ cups all purpose flour, ½ cup sugar, 2¼ teaspoons baking powder and ½ teaspoon salt to a small bowl - and whisk to combine.
In a medium bowl, whisk together ½ cup plus 2 tablespoons milk, 2 tablespoons canola oil, 1 large egg and 2½ teaspoons vanilla extract. Add the flour mixture to the wet ingredients and stir just until combined.
Pour the cake batter into the prepared pan and spread into an even layer with a rubber spatula.
Add the crumble topping evenly across the batter. (It will look like you've got WAY TOO MUCH topping -- but use it all.) Sprinkle the crumble with ¼ teaspoon sea salt.
Bake for 35-40 minutes until the cake rises and the topping bakes into the dough.
Remove from the oven and cool slightly in the pan. Run a knife along the edge to loosen the cake and lift it from the pan to a cutting board. Cut into squares. Sprinkle with 2-3 tablespoons confectioner's sugarf desired and serve.