Place broccoli florets and 1/3 cup water in a large microwave-safe bowl. Cover and microwave on HIGH for 3 minutes. Remove and drain any liquid.
In a medium-size skillet over medium-high heat, melt butter. Cook about 3 minutes, until golden brown, swirling pan often to prevent burning. Stir in almonds. Remove from heat. Pour browned butter over broccoli in bowl. Add onions and toss to combine. Serve immediately.