This is the EASY way, using a cake mix (reinforced so it's richer and a little denser) ~ with a vanilla pudding mix filling ~ and your choice of super easy CHOCOLATE GANACHE-style toppings.
It can be made with sugar or sugar-free products. In fact, the photos are of the sugar-free one that I made for my husband. Also my TIP to have even layers which don't rise too much in the center while baking.
Easy BOSTON CREAM PIE (If you want to be "fancy", you can spell it "CREME")
1 box yellow, butter or sugar-free yellow cake
4 eggs (actually 1 egg more than called for on package, which totaled 4 eggs for Pillsbury sugar-free)......................................................... 1 tsp. vanilla extract
1 cup any milk (I like unsweetened vanilla cashew or almond milk) ~or~ you can use
3/4 cup milk ~plus~ 1/4 cup caramel or Creme Brulee flavored liquid coffee creamer (actually, you're substituting all water called for on package with milk and/or creamer, but this is the measurement on the Pillsbury sugar-free)
5-1/2 TB melted butter (substituting oil called for on your package w/melted butter)
Preheat oven to 350. Spray 2 9"or 10" round pans with non-stick baking spray (containing flour) and set aside.
Put all the cake ingredients into your electric mixer bowl and beat about 2 minutes until smooth & fluffy. Divide evenly into your 2 prepared pans and smooth the tops. TIP: I always smooth from the inside out (with the back of a small spoon), with a little lower in the middle ~ because cakes always seem to rise more in the center and this will help keep it more even as it rises. See photo above. **
Give each pan a quick smack on the counter to break any air bubbles inside and put into the oven. Bake about 30-33 minutes, or until a cake tester comes out clean. Let them cool completely (in the pans) on a rack, before taking them out & assembling.
VANILLA PUDDING FILLING
1 small package vanilla or French vanilla instant pudding (sugar or sugar-free)
1-1/2 cups any kind of milk (and could substitute some milk with flavored liquid coffee creamer as in cake, but I don't do this for the filling)
2-3 envelopes unflavored gelatin (i.e. Knox)
Put the pudding mix & milk into a medium bowl (or use your mixer bowl ~ no need to wash it first) ~ and whisk/beat for about 30 seconds. Then stop and sprinkle the packets of unflavored gelatin evenly over the top ~ whisk/ beat again for about 1 minute or so, until thoroughly blended. Then stick it into the fridge to chill while cake layers bake & cool. (If it's still too loose later, you can whisk another packet of unflavored gelatin in there and let it sit in the fridge another 10 minutes to firm up.)
You have SO MANY options here ~ so whatever makes your life easier is fine! The very easiest option is just to put about 3/4 cup CHOCOLATE or CHOCOLATE FUDGE canned frosting (sugar or sugar-free) into a glass bowl and microwave about 20 seconds. Stir / whisk it smooth. Then spread just on top of the filled layers (but let some drip down the sides). If it's too liquidy, just stir in a little more from the can to thicken it up.
TIP: Whatever you do for chocolate ganache, I always add about 1 tsp. instant coffee or espresso powder before I heat it up, to intensify the chocolate flavor.
Or ~ you can melt about 3/4 cup dark or semi-sweet (or Hershey's sugar-free) chocolate chips in a glass bowl in the microwave (about 45 seconds) ~ whisk in about 1 TB milk, cream or that old flavored liquid creamer again! If you need more liquid, then add it gradually (maybe 1 tsp. at a time).
If you've made too much, you can actually store this in a covered glass dish in your refrigerator to use another time. Add a little milk before reheating about 40 seconds in microwave (and then stir in more chocolate, if you need it, to the microwaved milk).
Put one totally cooled layer UPSIDE-DOWN on a serving plate (this is so you'll have 2 even flat sides together in the middle). Spread the filling evenly on the bottom layer up to about 1/2" from the edge. Put the top layer on the filling. Press down very gently. With an offset spatula or butter knife, run it around the sides of the layers, scraping off the filling that's oozing out ~ and using that to fill in any "holes" or gaps. Then go back and smooth the filling all over. Spread CHOCOLATE GANACHE evenly over the top layer. If you want, you can let a little bit drip down the sides. .... and that's it!
It should be kept refrigerated.