... We have measured radio flux densities of BL Lacertae ( B2200+420 ) with the RATAN-600 radio telescope at 4.8, 7.9, 11.2 and 21.7 GHz during 6 October - 20 November, 2012 to study the detected ( ATel #4557, #4565, and #4568 ) flare. ... On 12 November flux density had notably risen to 8.30 +/- 0.19 Jy at 7.7 GHz, to 9.86 +/- 0.09 Jy at 11.2 GHz and to 11.70 +/- 0.3 Jy at 21.7 GHz. ... The spectral index changed from -0.08 +/- 0.02 to +0.23 +/- 0.02 at 11.2-21.7 GHz for October to November flux points...