This is called "Malzbier" in German. I used to drink it heaps as a kid, it's very sweet and malty. I found a recipe in German but haven't tried it out yet.
Quick summary of the recipe:
Dark Munich 70%
German Pilsner 25%
Dark Caramel 5%
2 noble hops additions, 5% AA for a total of 20 IBU
Infusion mash as normal, boil for 90 minutes. (calculate approximate loss of 10% wort volume)
Cool and pitch ale yeast at 20°C, after a few hours cool down to 0-1°C. (I think you should get between 0.5 and 1% alcohol). Lager for some time. (again, not very precise). Dextrose may be added at this point.
The recipe doesn't state whether to pasteurise the beer, but I guess you could heat to 60°C to kill the yeast and then chill and keg.