Create an ultra-premium gourmet burger advertising poster for a fictional brand "PRIME STACK". FORMAT: 4:5 vertical, bold appetizing commercial layout. SUBJECT: a towering juicy double cheeseburger with melting cheddar, crisp lettuce, glossy brioche bun and flying sesame seeds, dramatic mid-air ingredient splash of sauce droplets. BACKGROUND: warm charcoal-to-amber gradient, smoky grill atmosphere, soft ember glow. LIGHTING: appetizing crisp highlights, juicy glossy reflections, mouth-watering contrast. TYPOGRAPHY: bold condensed sans-serif logo "PRIME STACK" top-center, tiny tagline "Stacked to perfection" bottom-right. FINISH: 8k, hyper-realistic food photography, irresistible commercial finish.