Also kind of cheating since I'm not eating these now, I made them a few days ago. But I also like pancakes.
The secret to getting the darker outlines is to use a squirt bottle to draw them first, but you also have to add some sodium bicarbonate to the batter. This deprotonates the amino acids in the batter and increases the rate of the maillard reaction which is what causes browning. Same effect as is used in pretzels or lye rolls (though they are dipped in sodium hydroxide solution) like these ones I made a few weeks ago.