Preheat oven to 350 degrees.
Pour melted stick of butter into a lightly greased 8 in x 8 in baking pan. Sprinkle with brown sugar and walnuts.
Remove pear halves from can and reserve juice. Slice pears and evenly arrange over brown sugar and walnuts.
Cream softened butter and sugar until light and fluffy. Beat in the molasses, egg, and 1/2 c reserved pear juice.
Combine flour, cinnamon, allspice, ginger, baking powder, and baking soda. Add to creamed mixture and stir until well combined.
Spread the batter evenly over the pears.
Bake for 35-40 minutes or until an inserted toothpick comes out clean. Cool cake for 15 minutes before inverting onto a serving plate. Make sure you have a good grip before inverting! We enjoy this cake with vanilla ice cream and a drizzle of caramel sauce but you can serve it however you wish :)