In large bowl, cream butter and sugar until light and fluffy, 5-7 minutes. Add eggs, 1 at a time, beating well after each addition. In another bowl, whisk together the next 5 ingredients; add to creamed mixture alternately with pumpkin, beating well after each addition., Line a 5-qt. round slow cooker with heavy-duty foil extending over sides; spray with cooking spray. Spread batter evenly into slow cooker. Cook, covered, on high until a toothpick inserted in center comes out clean, about 2 hours. To avoid scorching, rotate the slow-cooker insert a half turn midway through cooking, lifting carefully with oven mitts. Turn off slow cooker; let stand, uncovered, 10 minutes. Using foil, carefully lift cake out of slow cooker and invert onto a serving plate., Drizzle caramel syrup over cake; top with pecans. Serve warm.