In a large bowl with a mixer, beat butter and sugar until very well mixed and no lumps remain. Add milk, yogurt, egg, and vanilla; beat just until blended. Add flour, soda, and pecans; stir until mixture is evenly moistened.
Spoon batter equally into 12 buttered or paper-lined muffin cups (2 1/2 to 2 3/4 in. wide).
Bake in a 425° regular or convection oven until muffins just begin to pull from pan sides and spring back in the center when lightly pressed, about 15 minutes.
Cool muffins in pan about 5 minutes, then invert onto a rack and turn rounded side up. Serve hot, warm, or cool. If making up to 1 day ahead, wrap cool muffins airtight and store at room temperature; freeze to store longer. To reheat, seal in foil and bake in a 350° regular or convection oven about 10 minutes.
Nutritional analysis per muffin.