Preheat the oven to 350 degrees F. Heat a cast-iron skillet over medium-high heat.
For the filet mignon: Sprinkle both sides of the steak with ample amounts of salt and pepper. Add the olive oil to the skillet and then add the steaks. Sear each side until a nice char appears and the steak is medium-rare (125 to 130 degrees F), 5 to 6 minutes. Let the meat rest for 10 to 15 minutes.
For the crostini: Drizzle each side of the baguette slices with olive oil and sprinkle with salt and pepper. Place on a baking sheet and toast in the oven until lightly golden, 7 to 10 minutes. Once toasted, schmear a thin layer of gorgonzola on each crostini.
For the crostini build: Thinly slice the rested steak and top each gorgonzola-schmeared crostini with slice or 2 of filet. Spoon a bit of Rosemary Pesto on top and garnish with the tomato slices and sea salt. Seal the deal with a little Dean Martin and a good glass of wine.
In a food processor, process the herbs, Romano cheese, nuts, garlic and some salt and pepper until smooth. Scrape down the sides of the bowl with a spatula and, with the motor running, stream in the olive oil. Taste and adjust the seasoning as necessary.