For malt extract:
Märzen is an amber lager often associated with autumn. This style is not the same as Festbier, which is the beer served during Oktoberfest celebrations in Germany. Märzen is a darker amber color than Festbier, with more malt character and slightly higher alcohol.
2021 BJCP 6A - Märzen characteristic ingredients: "Grist varies, although traditional German versions emphasized Munich malt. The notion of elegance is derived from the finest quality ingredients, particularly the base malts. A decoction mash is traditional, and enhances the rich malt profile."
Vital statistics: OG: 1.054 – 1.060, FG: 1.010 – 1.014, IBUs: 18 – 24, SRM: 8 – 17, ABV: 5.6 – 6.3%
Continental pilsner malt should be the foundation. Significant proportions of Vienna and Munich malt should be included. Hofer (2022) describes some commercial brewers using 50% pilsner, 25% Vienna, and 25% Munich or 50% pilsner with 50% dark Munich. Similarly, Daniels (2001) recommends that 80 to 90% of the malt bill should be pilsner, Vienna, and Munich, with his analysis averaging 41% Vienna and 21% Munich. The remaining malts can be small amounts of crystal malts like CaraPils and/or CaraMunich, but this should be kept small. Avoid excessive crystal malt flavor.
The traditional mashing method is decoction to enhance caramel and melanoidin character. Step mashes and single-step infusion mashes are more common in modern commercial brewing. In these, decoction-like character might be partially achieved through using small amounts of crystal malts, CaraRed, or Melanoidin malt. Tiny amounts (1% or less) of Carafa or other roasted malts may be used for color adjustment.
The hops should be German or continental European varieties: Hallertau, Tettnanger, Spelt, and possibly Saaz. American hops bred from classic German hops could be a substitute. Avoid high hop flavor and aroma because the focus should be on malt character. Aim for a BU/GU ratio around .38.
Use a clean fermenting lager yeast that produces low diacetyl. The beer should attentuate well and be easy-to-drink to avoid being overly sweet. High final gravity or excessive sweetness is a fault.
Beer-analytics.com Märzen analysis
Daniels, R. (2001). Designing great beers: The ultimate guide to brewing classic beer styles. Brewers Publications. p. 335 - 337.
Hofer, F. (2022, September). Germany's beers of autumn: Brew your own Märzen and festbier in time for Oktoberfest. Brew Your Own, 48 - 53.
Zainasheff, J., and Palmer, J.J. (2007). Brewing classic styles: 80 winning recipes anyone can brew. Brewers Publications. p. 70 - 71.