Turn the oven to 350 degrees.  Grease a 9×13 pan.  As you will be using the broil setting for the topping, I don’t suggest using parchment paper unless you cut it very short.  Otherwise, it can burn very quickly while making the topping if there’s too much overhang.  

Blend cracker crumbs, flour and baking powder in a small bowl; set aside.

Beat butter and sugar in a large bowl with an electric mixer at high speed until light and fluffy. Add eggs, one at a time, beating well after each addition. Stir in vanilla.

Alternately add flour mixture and milk, beating well after each addition. Put batter into the pan, smoothing the top.  

Bake for 25 minutes or until done. 

Meanwhile, make the topping.  Melt butter and add the rest of the ingredients, mixing well.  

Once the cake is finished baking, remove it from the oven and turn the heat to broil.  Spread topping evenly over cake.  Return to the oven and broil for 2-3 minutes until the topping starts to bubble.  Watch carefully, as it will burn quickly if left unattended!