Here's my first draft of a recipe for you. I'm an AG brewer, so maybe some of the PM or extract brewers will chime in here too. Remember, this isn't going to be a pilsner, but a koelsch. I've intentionally kept the hop values relatively low.
The water must be very soft, so I'm going to recommend using all RO or distilled water (6 Gals).
Ingredients:
For the mash:
2 lbs Global Kolsch malt (Milled Grain)
2 oz Acidulated malt (Milled Grain)
1/8 tsp Calcium Chloride
For the boil:
4 lbs Pilsner DME
1 oz German Hallertau Hops (as First Wort Hop, placed in pot prior to boil and left for duration of boil)
.5 oz Czech Saaz hops (30 mins)
.5 oz Czech Saaz hops (15 mins)
1/2 Whirlfloc tab (15 mins)
Directions: (Assuming mash in a pot or BIAB) Bring 3 qts water and Calcium Chloride to 150*F, then dough in your grains. Stir the grains a bit. Raise temp if necessary and hold grain temp between 144*F and 149*F for one hour (for Koelsch the mash temp will be a little lower than the usual 152-154*). Dump the mash through a strainer (or remove your grain bag) to another pot. Heat another 2 gallons of water to 168*F. and pour slowly over your grains, recirculate all the wort a few times through the grains.
Lightly press the grains (but don't squeeze) to release more water, then set the grains aside. Add the Hallertau hops to the wort, and another 3qts of water, and bring to a boil. After 30 mins add .5 oz Saaz hops. After another 15 mins add the rest of the hops, the DME and whirlfloc. Turn off heat and add 2 gallons of cold water to cool, put in an ice bath if necessary to get temp to 68f. Take a gravity reading, OG should be about 1.046. Add yeast and ferment.
If you want to do this recipe, PM me when you are ready with your address, and I'll send you the Acid malt, calcium chloride and whirlfloc so you don't need to buy them for such small amounts.
Edit: Forgot to mention which yeast. When I make Kolsch, I use whitelabs Kolsch yeast wlp029. If you use this, you will need to make a starter. But if you want to use dry yeast, I think Nottingham would work well.
Ferment the first 3 days at 68*F, then lower the temp to 60*F for at least 4 weeks. No need to ever transfer this to a secondary. Take a gravity reading before bottling. FG should be about 1.012.