1) Preheat the oven to 350°F. Lightly grease a 9" x 13" pan.
2) Beat together the butter, sugar, and salt till smooth.
3) Add the eggs one at a time, beating well after each addition.
4) Add the baking powder, then add the flour alternately with the milk, starting and ending with the flour. Mix until smooth. Stir in the grated lime rind or lime oil.
5) Spoon the batter into the prepared pan, smoothing the top with a spatula.
6) Bake the cake for 25 to 33 minutes, or until the top is starting to brown and a cake tester inserted into the center comes out clean.
7) While the cake is baking, make the glaze by stirring together the lime juice and sugar. Set it aside.
8) Remove the cake from the oven, and set it on a rack. Use a skewer or toothpick to poke the top all over. Don't poke all the way to the bottom of the pan; just about halfway down.
9) Stir the glaze to combine, and immediately brush it onto the hot cake; be generous. Let it sink in for about 5 minutes, then brush on more glaze, continuing until all the glaze is used up.
10) If you're using the optional sugar topping, shake the coarse sugar in a jar with the lime oil, till well combined. Sprinkle the sugar atop the glazed cake, gently pressing it in with your fingers.
11) Allow the cake to cool completely before slicing.
12) To make the raspberry topping, stir together completely thawed raspberries with pie filling enhancer (if you're using it), and sugar to taste.
13) Serve squares of cake with a dollop of raspberry sauce on the side.
Yield: about 2 dozen servings.