For malt extract:
2021 BJCP 4B - Festbier characteristic ingredients: "Majority Pils malt, but with some Vienna or Munich malt to increase maltiness. Differences in commercial examples are mostly due to different maltsters and yeast, not major grist differences."
Vital Statistics: OG: 1.054 - 1.057, IBU: 18 - 25, SRM: 4 - 6, FG: 1.010 - 1.012, ABV: 5.8% - 6.3%
Continental pilsner malt like Weyermann is essential. Jamil Zainasheff suggests a malt composition of 1/3 Vienna, 1/3 Munich, and 1/3 Pilsner. Gordon Strong suggests 60% to 80% pilsener malt, with the rest being Vienna and/or Munich. Small amounts of crystal malt like CaraPils, CaraVienna, or CaraMunich are possible, but some experts feel that these are "out of place."
The hops should be German or continental European varieties. Hallertau is the most recommended in the reviewed recipes followed by Tettnang. Using Magnum for bittering and Hallertau for aroma and flavor is a possibility. Saaz is sometimes included as a noble hop possibility, but one source feels that it is too spicy for this style. Most recipes have small amounts of late hop additions.
The yeast should be a clean fermenting lager yeast that produces low diacetyl. Fermentation practices that minimize diacetyl should be used, such as a diacetyl rest.
Beer-analytics.com festbier analysis
Rodammer, N. (2015, March - April). Oktoberfest: Brew now, celebrate later. BYO, 58 - 64.
Strong, G. (2016, January - February). The modern beer of Oktoberfest: Festbier, a lighter Oktoberfest. BYO, 30 - 34
Zainasheff, J. (2014, October). Oktoberfest: A rich, toasty German lager. BYO, 23 - 27