Melt the butter in a skillet. Add the pretzel pieces and stir to coat. Sprinkle with 2 tablespoons of brown sugar and cinnamon. Mix to coat.
Remove from heat and set aside to cool completely.
Wash and hull the strawberries. Cut the strawberries into quarters, place in a bowl and gently toss them with the remaining two tablespoons of brown sugar.
Whip the heavy cream, powdered sugar, and vanilla extract until stiff peaks form.
Gently fold in the yogurt and sour cream.
Set aside a few strawberry and pretzel pieces for garnish.
In a trifle bowl, place a layer of strawberries on the bottom, cover the strawberries with a layer of the sugared pretzel pieces. Add a layer of cream.
Repeat ending with the cream on top. Garnish with the reserved strawberry and pretzel pieces.