Blueberry Muffins

Muffins:

2 cups (or less) fresh blueberries (raspberries are great too in this!)
1 1/8 cups plus 1 tsp. sugar
1 Tbsp. water
2 1/2 cups All-purpose flour
2 1/2 tsp. baking powder
1 tsp salt
2 eggs
4 Tbsp. (1/2 stick) butter melted and cooled
1/4 cup oil
1 cup buttermilk
2 tsp. vanilla

Preheat oven to 425 degrees.

Bring 1 cup blueberries, water and 1 tsp. sugar to simmer in small saucepan over medium heat.  Cook, mashing the blueberries with potato masher or fork.  Frequently stirring until blueberries are broken down and mixture is thick and reduced by halfway.  Transfer to smaller bowl, cool to room temperature.  Whisk flour, baking powder and salt together in large bowl.  Whisk remaining sugar and eggs together in medium bowl until thick and combined well.  Slowly mix in butter and oil until combined whisk in buttermilk and vanilla.  Using a rubber spatula, fold egg mixture and remaining cup of blueberries into flour mixture until just moistened (batter will be very lumby with few spots of dry flour, do not overmix.)

Using a cookie scoop or spoon to divide batter equally among the tins (batter should completely fill cups and mound slightly.)  Spoon teaspoon of cooked berry mixture into center of each mound of batter.  Using a chopstick or skewer, gently swirl berry filling into batter (figure 8 motion).  Sprinkle lemon sugar topping or struesel topping over muffins.

Bake until golden brown and firm, 17 to 19 minutes.  Cool 5 minutes.  Transfer to wire rack for five minutes.

Lemon Sugar Topping:
1/3 cup sugar
1 1/2 tsp. finely grated lemon zest

Combine.

Struesel Topping:
3 Tbsp. white sugat
3 Tbsp. brown sugar
1/3 cup flour
5 Tbsp. melted butter

Combine.