Preheat your Yoder Smokers YS640s Pellet Grill to 375ºF, set up for indirect grilling.
Combine the flour, baking soda, baking powder and Jacobsen Salt Co. Kosher Sea Salt and mix well.
Combine the sour cream, maple syrup and vanilla extract and mix well.
Combine the ingredients for the topping and mix well.
Place the sugar and butter in the bowl of a stand mixer. Using the whisk attachment, whisk over high speed until fluffy and light in color.
Reduce the speed to medium and add the eggs one at a time, waiting to add the second until the first is fully incorporated. Scrape down the bowl and whisk again to evenly distribute ingredients.
Reduce the speed to low and add half of the dry ingredients. When add dry ingredients are incorporated, add the wet ingredients. When all wet ingredients are incorporated, add the remaining dry ingredients. When add ingredients are incorporated, scrape down the bowl and mix briefly again to distribute ingredients.
Pour half of batter into a greased half sized foil pan. Spread evenly with a wet spatula. Sprinkle half of the topping over the batter. Top with the remaining batter. Again, spread evenly with a wet spatula. Sprinkle the remaining topping over the batter.
Transfer the pan to the second shelf of the grill. Bake until a toothpick inserted into the center of the cake comes out mostly clean, about 45 minutes.
Remove from the grill and let cool slightly before slicing to serve.