FOR THE CAKE:
Preheat your oven to 350°F.
Line a 9 inch baking pan with parchment paper.
In a large bowl combine all cake ingredients and mix (with an electric mixer) until smooth and fluffy, about 3 minutes.
Pour Batter into baking pan.
Bake for 35 minutes.
Let cake just cool for 2 minutes, then poke lots of holes with the end of a wooden spoon into it.
Microwave the strawberry jam on high for about 45 seconds.
Stir and pour over cake, making sure to fill the holes.
In a medium saucepan combine milk, sugar, peanut butter, cornstarch and egg yolk.
Bring to a boil (while stirring).
Boil until the mixture gets really thick, about 10 minutes (never stop stirring).
Let pudding cool down for 5 minutes, then spread gently over the cake.
Place in fridge until completely cooled.
Top with some whipped cream before serving (optional).