Preheat oven to 375°. In a large bowl, cream butter and sugar until light and fluffy, 5-7 minutes. Beat in eggs, 1 at a time. Beat in molasses and vanilla. In another bowl, whisk together flour, baking powder, cinnamon, salt and baking soda; gradually add to creamed mixture. Stir in oats and pecans., Drop dough by tablespoonfuls 2 in. apart onto greased baking sheets. Bake until edges are firm, 10-12 minutes. Cool on pans 3 minutes. Remove to wire racks to cool.