Brown the butter: In a small saute pan over medium heat, melt the butter. Continue stirring and cooking the butter after it has fully melted; it should start to bubble.As the butter cooks, the color will slowly change to a golden brown and it will smell nutty and caramelized. Pull the butter off the heat once a light brown color has been reached, about 3-4 minutes total.
Brush both sides of each piece of bread with a little olive oil. Grill over high heat until toasted, 1-2 minutes per side.
Thickly slice the tomatoes. Layer tomato slices over the grilled bread.
Drizzle the browned butter over the tomatoes, then sprinkle with salt and pepper.