In the bowl of a food processor, add the livers and onion and pulse until the mixture is a liquified, scraping down the sides of the bowl as necessary. Transfer the liver and onion mixture to a large bowl, then whisk in the eggs, flour, ¼ cup plus 2 tablespoons of oil, salt, and pepper.
Heat a small nonstick skillet over medium-low heat. Brush the surface lightly with oil as the pan heats and when the pan is hot, lift it away from the direct heat and ladle in enough batter to coat the surface of the pan in a thin layer, all the way to the edge of the pan (about ¼ cup), swirling the batter until it forms as perfect a circle as possible. You want a thin crepe, so try to add as little batter as necessary to reach the edges of the pan after swirling. Return the pan to the direct heat and cook until the crepe is set, slightly browned on the bottom, and crisp around the edges, about 3 minutes. Use a spatula, a fine-tipped wooden skewer, or even your fingers to gently lift and flip the crêpe to continue cooking until the other side is slightly browned, about 2 minutes more. Flip the crêpe again, cook for another 30 seconds to crisp, then transfer the crêpe to a plate and set aside while you continue cooking the rest of the batter, stacking the crêpes atop one another as you go. Once all the crêpes are cooked, set them aside to cool to room temperature.
Meanwhile, make the filling: Set aside a generous tablespoon of dill for garnish, then, in a medium bowl, add the mayonnaise, garlic, and the remaining dill. Season with kosher salt to taste and whisk to combine. Cover and refrigerate if you are not using immediately.
When the crêpes are cooled, assemble the pie. Place one crêpe on a medium plate and spread with a thin layer of filling (about 3 tablespoons). Layer a second crêpe atop the first. Continue layering all of the crêpes and filling in this manner to make a tidy stack. (You may wish to ensure you have enough filling by laying out all the crêpes at once and dolloping even amounts of filling onto each before proceeding with the stacking.) Decorate the top layer generously with the reserved dill. Tent the pie loosely with foil and transfer to the fridge. Let the pie chill in the fridge for at least 2 hours or up to one day. Cut into wedges and serve, either chilled or warmed gently in the oven.