Preheat the oven to 350°F. Grease and flour a 9x13-inch pan. See Note #4 below for parchment use.
Combine the pecans, brown sugar, cinnamon, oats, melted butter and pinch of salt in a small bowl. Mix until it looks like damp sand, then set aside.
Beat the butter and granulated sugar in a stand mixer on medium-high speed for a full 4 minutes, until pale and fluffy.
Add the eggs one at a time, beating 30 seconds after each and scraping down the bowl. Add the sour cream, vanilla and almond extract, then beat until just combined.
Whisk together the flour, baking powder, baking soda and salt in a separate bowl. Fold into the butter mixture until just combined.
Spread half the batter evenly in the prepared pan. Sprinkle with half the streusel. Add the remaining batter in spoonfuls and spread gently to cover, then finish with the remaining streusel.
Bake at 350°F for 55 to 65 minutes, until a skewer inserted in the center comes out with a few moist crumbs, not wet batter. Start checking at 50 minutes.
Cool completely before making the glaze.