Tried this recipe this morning. And it was GOOD. (Only "good" with our standard. We are still looking for that "excellent" blueberry muffin that uses frozen berries!) I have been making many different blueberry muffin recipes and I reckon this one is to keep for now...(Until I get fresh blueberries to try BB's?)

Note: I didn't make the topping as we don't like nuts.
I bake these muffins in Texas muffin tins (6 muffins) and the baking time was about 15 minutes longer.
========================
Lemon Sour Cream Blueberry Muffins
(From Baker Boulanger)

Topping: (Haven't tried this topping as we don't like nuts.)
2 tbsp. unsalted butter
2 tbsp. flour
3/4 cup finely ground walnuts
1/2 cup white sugar
1 tsp. cinnamon
1/2 tsp. fresh nutmeg

Combine ingredients by tossing with a fork to achieve a crumbly mixture. Set aside.

Batter:
1/4 cup (2 oz.) unsalted butter - room temperature
1/4 cup (2 oz.) vegetable shortening - room temperature
(**As I don't have vegetable shortening, I just douobled the butter.)
1 cups sugar (originally called for extra 1/4 cup.)
1 egg
1 tsp. vanilla
juice of one lemon (I used a large lemon)
zest of one lemon - finely grated
2 tbsp. water (**I used full crema milk.)
1 cup sour cream/plain yogurt (**I used yogurt as I ran out of sour cream.)
2 1/4 cups flour
1 tsp. baking soda
1 1/4 cups frozen or fresh blueberries (** I used forzen ones.)

Preheat oven to 350 F. Line a 12-cup muffin tin with paper liners.

Cream the butter with the shortening until mixture is smooth and paste-like. Blend in sugar, then egg, vanilla, lemon juice, zest and water. Stir in sour cream. Mix baking soda and flour and blend into batter. Fold in berries by hand. Scoop into prepared muffin cups. Sprinkle the tops with equal portions of streusal topping.

Bake until done - 28-32 minutes.

One dozen muffins.