• Get out and organize all of your ingredients.
• Grease 9X13 pan and set aside.
• Preheat your oven to 350℉.

Make the Streusel

• Stir together the dry ingredients (Flour / Sugar / Cinnamon / Salt)
• Using a pastry cutter - cut in the cold butter.
  
• Stir in the Oats and the Lemon Zest.
• Set Streusel aside.

Prepare the Cake

• Mix the Dry ingredients together in a bowl and set aside.
• In your mixer - blend the oil and the room temp butter till well combined.
• Add in the sugar and whip for a while - trying to get a whippy texture. This mixture will not be so light and creamy as it is part oil - and not the typical cake butter / sugar creaming... Try to get air into the mixture, though.
  
• Add the eggs one at a time, mixing between each - scraping the bowl down as needed.
• Add the sour cream - scraping the bowl down as needed.
• Add the dry ingredients, stirring just until incorporated. (Don't over mix - you don't want the flour to develop gluten.)
  
• Layer the cake - first layer 1/2 of the batter. Dollop the cake batter into the pan and then carefully spread as evenly as you can.
  
• Second layer - is a bit less than 1/2 of the streusel. (Putting more streusel makes it hard to cover with the remaining batter.)
  
• Third layer - is the last of the cake batter - again dollop the cake batter around and then carefully spread. It will be a bit tricky since the streusel is going to stick and make it harder to cover readily.
  
• Fourth / top layer - is the remaining streusel.
  
• Bake at 350℉ for 29 or 30 minutes in your 9X13.

Make the Glaze

• Mix up lemon juice and powdered sugar. After you get the consistency you want - put the glaze into a zip lock bag and set aside.
  
• After the cake has totally cooled, cut a corner off your zip lock bag of glaze and drizzle the glaze on the cake.
  
• Serve the cake to friends and family !