For the topping: Add 1/2 cup of the blueberries to a medium bowl with the sugar, honey, lemon juice and cardamom and let sit, stirring every 10 minutes or so and mashing slightly, until the juices are a vibrant pink color, about 1 hour. Fold in the remaining blueberries, coating them in the sauce until shiny.
For the blintzes: Meanwhile, in a blender or food processor, combine the milk, flour, salt and eggs and blend until smooth. Let the mixture sit at room temperature for 30 minutes.
Coat a 9- or 10-inch nonstick skillet with a thin layer of oil and heat over medium heat. Add 1/3 cup batter to the skillet and tilt it so that it distributes evenly into a round. Cook until the top is set and the bottom is slightly browned and pulls away easily from the skillet, 60 to 90 seconds. Use an offset spatula to transfer it to a plate or work surface (correct, you will not be flipping these). Repeat this process, stacking the cooked blintzes and separating them by sheets of parchment paper.
For the filling: In a bowl, mix together the cream cheese, ricotta, honey, lemon zest and juice, almond extract, cardamom, salt and egg until combined.
To assemble: Place a blintz browned-side up on a work surface. Spoon 1/4 cup filling slightly below the center line of the blintz. Fold the bottom third of the blintz up over the filling and then fold in the sides. Bring the top third of the blintz down over the filling to seal. Set aside and repeat with the remaining blintzes.
In a large skillet, heat a thin layer of oil over medium-high heat until shimmering. Fry the blintzes a few at a time until golden brown, 2 to 3 minutes on each side, adding additional oil if the needed. Transfer to a serving plate, top with the blueberry sauce and enjoy.