1. 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.
2. Spoon batter equally into 12 buttered or paper-lined muffin cups (2 1/2 to 2 3/4 in. wide).
3. 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.
4. 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.