Stir together baking mix, sugar, milk, and 3 tablespoons butter until a soft dough forms. Turn out onto a lightly floured surface; knead 3 to 4 times.
Pat dough to a 1/4-inch thickness; cut with a 2 3/4-inch round biscuit cutter. Place on lightly greased baking sheets.
Combine pecans, brown sugar, cinnamon, and remaining tablespoon butter; pat onto biscuit tops.
Bake at 375° for 12 to 15 minutes or until lightly browned.
Cinnamon-Crunch Shortcakes With Fruit Compote: Prepare 1 recipe Cinnamon-Crunch Shortcakes. Melt 1 tablespoon butter in a large nonstick skillet over medium-high heat. Stir in 1/2 cup apple juice, 1/4 cup firmly packed brown sugar, 2 ripe Bosc pears, peeled and sliced; 2 Rome apples, peeled and sliced; 1/4 cup dried cranberries; and 1/4 teaspoon ground cinnamon. Bring to a boil; reduce heat to low, and simmer, stirring occasionally, 10 to 15 minutes or until fruit is tender. Split each baked shortcake in half. Layer half of biscuit halves with fruit compote and whipped cream; top with remaining biscuit halves.