I tried making this the other night. But the outcome had a burnt taste and it seemed as though the color of the liquid was at the amber stage lon...

Thermometer can be off or might need to be calibrated. If the thermometer is way off, like by 10 degrees, this can mean the difference between hard ball stage, 300F, and burnt candy.

The ingredients, except baking soda, go into the pot. Put the pot over the heat. The heating element does not need to be preheated, in this method it won't make a difference. The important thing is that the mixture reaches the hard ball stage or 300F, which is the reason the thermometer needs to be accurate. Yes, all the baking soda goes into the hot mixture, off heat. The baking soda will react with the acidic maple syrup and produce the bubbles in the candy. In fact, the mixture is going to foam up dramatically, so make sure your pot is big enough to handle the increase in volume.

I've made honeycomb but not this specific recipe, so did it seem like the sugar syrup was deep enough for the thermometer to get a good reading? The bulb or digital sensor would need to be down in the sugar, not at the very top surface. I generally need to tilt the pan to get a pool deep enough for an accurate reading. You can test the thermometer in ice water (32 F) and boiling water (212 F sea level) to get an idea if it's readings are far off. If the sugar syrup has turned amber in spots, swirl the pan to spread the hot spots and avoid local burned patches. If it was amber all over (and smelled burnt), most likely the thermometer reading was low and sight/smell were correct. The amber color of the syrup will be darker in color than the final candy pictured. Put the pan on the burner with the ingredients then turn the burner on. Take the pan off the heat after the sugar is amber (esp. since it sounds like you have electric) and add all the baking soda at the end.