For the topping, stir together zest from 1 lemon and 1/3 cup sugar until combined set aside.
Spray jumbo muffin tin with nonstick cooking spray.
Heat oven to 425 degrees.
Bring 1 cup blueberries and 2 teaspoon sugar to simmer in saucepan over medium heat. Cook mashing berries and stirring frequently, until berries have broken down and mix is thickened about 8 minutes. Cool to room temperature.
Whisk flour, baking powder, and salt together in large bowl. Whisk remaining sugar and eggs together until thick and homogeneous, less than one minute. Slowly whisk in butter and oil add buttermilk and and vanilla until combined. Fold egg mixture and 1 cup blueberries into flour mixture until moistened. DO NOT OVERMIX.
bake until muffins tops are golden brown and firm, check after 20-23 minutes.
spoon batter equally among prepared muffin pan (batter will completely fill cups) spoon berry mixture over batter and gently swirl mixture into batter. sprinkle lemon sugar over muffins.