We perform the systematic numerical study of high vorticity structures that develop in the 3D incompressible Euler equations from generic large-scale initial conditions. We observe that a multitude of high vorticity structures appear in the form of thin vorticity sheets (pancakes). Our analysis reveals the self-similarity of the pancakes evolution, which is governed by two different exponents $e^{-t/T_{\ell}}$ and $e^{t/T_{ω}}$ describing compression in the transverse direction and the vorticity growth respectively, with the universal ratio $T_{\ell}/T_{ω} ≈ 2/3$. We relate development of these structures to the gradual formation of the Kolmogorov energy spectrum $E_{k}∝\, k^{-5/3}$, which we observe in a fully inviscid system. With the spectral analysis we demonstrate that the energy transfer to small scales is performed through the pancake structures, which accumulate in the Kolmogorov interval of scales and evolve according to the scaling law $ω_{\max} ∝ \ell^{-2/3}$ for the local vorticity maximums $ω_{\max}$ and the transverse pancake scales $\ell$. ; Comment: 31 pages, 18 figures