Cut phyllo dough into the 12-inch squares, brush each sheet of phyllo with melted butter, stacking sheets on each other rotating slightly, use all sheets. Put the stacked sheets all at ones in 9-inch cake pan lined with parchment paper brushed with the butter. Gently push it into the corner and make a few vents in the bottom before baking.
Bake for 20 minutes on 350F. Take out and let slightly cool.
In meantime make the almond filling and slice the plums.
For almond filling mix all ingredient in the bowl and keep on the side.
Start with sliced plums in the middle of crust and continue in circle shape pattern.
Pour almond filling over plums.
Bake 60-65 minutes on 350F or until the custard is set, covering with foil towards the end to prevent burning.
Cool in the pan for 1-2 hours. Push pan bottom up, releasing cake from pan.
You can serve at room temperature after is cooled.
Use a sharp serrated knife to cut.
Make the day before and keep in the fridge, the crust will still stay crispy but it will get firm and give you a clean cut.