I'm in the middle of preparing our Mini for the Summer and there are some extensive repairs underway.

I am in the process of replacing the valve cover gasket, which may or may not be original. My question: other than the valve cover gasket, what other oil leaks at the front (vehicle's front) of the engine would cause this amount of oil leaking and build up?


I'm in the process of degreasing that area now. I had serviced the supercharger oil <20k miles ago, but I'll check the level while I have access, too.

 

I'll preface by stating that I'm not nearly an expert as you.
(To me), It appears that perhaps you are correct - Valve cover was leaking a bit. Dip stick 'O' ring might need replacing. From my previous experience : The oil pan gasket maybe leaking at the front.(?)...

I replaced mine with Felpro. And it still leaked a little in some areas. But probably my fault - Although I followed the torque sequence; I replaced mine while on jack stands.
For me - It was a PIA.

Nice that you have the car on a lift!